# What Order Should Well Water Treatment Systems Go In? Source: https://brictale.com/water/filtration/what-order-should-well-water-treatment-systems-go-in Published: 2026-08-25 Audience: Homeowner Published by Brictale, a consumer home-intelligence publication. https://brictale.com ## Short answer There is no safe universal chain. Start with the lab results and the exact manuals, keep cartridge filters after the pressure tank unless engineered otherwise, put UV after the manufacturer-required pretreatment, and verify every unit’s rated service flow, backwash demand, drain, sample point, bypass, and power needs. A quote is ready for review only when those constraints fit together without hiding an untreated branch. --- # What Order Should Well Water Treatment Systems Go In? **Short answer:** there is no safe universal chain. Start with the laboratory results and the exact manuals for the proposed equipment. Protect the pump-and-pressure controls, usually keep cartridge filtration downstream of the pressure tank, put required pretreatment before a UV unit, and check every stage for rated flow, pressure drop, backwash or regeneration demand, drains, sample points, bypasses, and power. The right order is the one that satisfies all of those constraints without silently routing drinking water around treatment. This is a quote-review and layout-planning surface for a private-well homeowner. It does not select equipment from a generic contaminant list, approve a plumbing design, or replace the local health department, a certified laboratory, the exact installation manual, or a qualified well, plumbing, electrical, or water-treatment professional. ## 1. Decide what “right order” has to accomplish The purpose of a treatment train is not to make every tank look tidy in a row. Each stage should do a defined job for a measured water problem while receiving water it can handle, preserving enough pressure and flow for the house, and remaining serviceable. Start by writing four facts at the top of the quote: 1. **What was found?** Record the laboratory analyte, result, units, sample point, collection date, and any reporting limit. “Bad well water” is not a usable design input. 2. **Where must it be treated?** Mark whole-house fixtures, outside faucets, irrigation, a kitchen drinking tap, refrigerator, and any separate pressure zone. Point-of-entry and point-of-use goals are different. 3. **What demand must be supported?** Record the home’s expected simultaneous flow, the well pump’s delivered flow if documented, pressure-switch cut-in and cut-out settings, and any storage, booster, cistern, or low-pressure device. 4. **What does each manual require?** Use the exact model number, revision, rated service flow, minimum and maximum pressure, pressure drop, backwash or regeneration flow, drain arrangement, electrical supply, sample point, and bypass instructions. EPA’s baseline private-well guidance is annual testing for total coliform bacteria, nitrates, total dissolved solids, and pH. EPA also says to test immediately after a significant nearby change, repair or replacement of a well-system part, or a change in water quality, and to use a certified drinking-water laboratory. [EPA’s testing guidance](https://www.epa.gov/privatewells/protect-your-homes-water) does not choose your equipment. It tells you why the lab result belongs before the equipment order. ### A quote is not ready when it only shows tank names Ask for a one-line purpose for every proposed stage. “Filter” could mean a disposable sediment cartridge, a backwashing iron filter, a carbon tank, a neutralizer, or a UV prefilter. Those devices have different hydraulic, drain, power, and maintenance consequences. | Proposed stage | Job it must perform | Evidence to attach before approval | What it must not be assumed to do | |---|---|---|---| | Sediment cartridge | Reduce the particles its rating and construction can handle | Lab or field evidence of particle problem; micron rating; clean and loaded pressure data; service interval | Prove bacteria, nitrate, iron chemistry, or chemical safety | | Backwashing media tank | Treat the named contaminant under its media and control settings | Lab result; media data; service and backwash flow; drain route | Operate correctly without adequate flow, pressure, or discharge | | Softener | Reduce hardness or other specifically claimed ions | Hardness and relevant chemistry; capacity and salt settings; service and drain data | Disinfect water or remove every dissolved contaminant | | Carbon tank | Reduce only the contaminants and capacity listed for that media and model | Exact performance claim, contact or service conditions, capacity, backwash or rinse needs | Be a universal chemical or germ barrier | | UV | Disinfect or reduce germs under its dose, flow, UV-transmittance, and pretreatment conditions | Exact UV model, maximum certified flow, pretreatment, alarm or shutoff behavior, sample point | Remove chemicals or make a failed upstream treatment plan safe | | Point-of-use stage | Treat one drinking-water outlet for a defined purpose | Outlet, membrane or cartridge claim, feed conditions, reject or drain needs, maintenance plan | Protect the shower, bath, ice maker, or every fixture unless it is plumbed to do so | CDC explains that treatment systems address different germs or chemicals. It describes UV as a germ treatment, says prefiltration improves UV performance, and says UV with prefiltration does not remove chemicals. [CDC’s treatment overview](https://www.cdc.gov/drinking-water/about/about-home-water-treatment-systems.html) is a scope boundary, not a product approval. {{visual:treatment-train-constraint-map}} ## 2. Lock the pressure-tank boundary before placing filters For a typical submersible-well layout, the first placement question is not “sediment before or after the softener?” It is “will this device interfere with the pressure switch’s ability to control the pump?” Boshart warns against installing a sediment filter between the submersible pump and pressure tank. Its explanation is specific: as a cartridge loads, the pump can build pressure against the restriction; if the pressure switch is after that filter, it may not see the pressure needed to shut the pump off. Boshart therefore places sediment filters after the pressure tank. [Read Boshart’s pump-and-pressure-tank explanation](https://support.boshart.com/can-sediment-filters-be-installed-between-the-pump-and-pressure-tank). Pentair gives a similar placement instruction for its PC600-P and PC1000-P whole-house systems: in a well-water home, the system should be installed following the pressure tank. [See the Pentair filter manual](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf). That is a manufacturer instruction for those models, not a universal rule that every engineered well device must be downstream. The practical homeowner rule is: - Treat a cartridge filter before the pressure tank as a stop-and-verify condition. - Ask the installer to identify the pressure switch, gauge, tank tee, pump discharge path, relief protection, and any check valve on the drawing. - Ask which exact manual or engineered design authorizes any pre-tank device. - Do not move a pressure switch, alter a pump control, or open a control box to test the theory. An exception may exist for a device designed as part of the pump or well system, a manufacturer-approved protective screen, or a professionally engineered arrangement. The exception belongs in the written scope with the model or design basis. “The installer always does it this way” is not an evidence trail. {{visual:pressure-tank-filter-boundary}} ### What you can safely observe From a dry, accessible location, you can photograph the existing layout, read an already-visible gauge, record the model plate, and note whether a filter is before or after the tank. Do not open energized controls, test live wiring, manipulate pressurized fittings, pull a pump, open a well, or enter a well pit or other confined space. Those actions belong to qualified professionals under the applicable equipment and local requirements. ## 3. Use lab results to decide pretreatment, not a universal ladder After the pressure-tank boundary, build the train from the water problem and the vulnerabilities of later stages. ### Particles and turbidity A sediment cartridge may protect a downstream valve, membrane, or UV sleeve, but a cartridge that loads quickly can become the home’s pressure bottleneck. The quote should state its nominal or absolute rating, housing size, rated flow, pressure drop at that flow, replacement trigger, and whether there is a pressure gauge before and after it. Do not infer that a smaller micron number automatically solves a chemical or biological problem. A backwashing filter has a different burden. It needs enough flow and pressure during backwash, a control valve that is configured for the media, and a drain that can accept the discharge. If the well pump cannot supply the backwash demand while maintaining safe operation, the equipment may not regenerate as designed even if the service-flow number looks adequate. ### Iron, manganese, sulfur, acidity, and other chemistry The sequence depends on the treatment chemistry. A pH-correction stage may be upstream of a device that needs a certain pH. An iron or sulfur treatment may need oxidation, contact time, or a specific media condition. A softener may be protected from fouling by upstream treatment, or a UV manual may require sediment after the softener. The order is therefore a compatibility graph, not a list copied from a neighboring installation. Use the exact lab result and manual to answer: - Does the proposed media require a pH range or pretreatment? - Does it create a waste or backwash stream? - Does it change the chemistry for the next stage? - Does the next stage tolerate that chemistry and any media fines? - Does a service or regeneration cycle interrupt treated water, and where is that water going? If the quote cannot answer those questions, hold the plumbing change and ask for a revised scope. A tank that is physically first may be chemically wrong; a tank that is chemically right may be hydraulically impossible. ## 4. Place softeners, carbon, and UV by their actual manual requirements There is a common pattern in which conditioning precedes a final germ-control stage, but the final layout must come from the exact manuals. The VIQUA D4, E4, and F4 family manual is a useful example of why. It identifies pretreatment, shutoff valves, optional bypass, and raw and post-UV sample valves. It specifies a 5-micron nominal sediment filter before the UV system and after any water-softening equipment. [See the VIQUA installation manual](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf). For a different UV model, use that model’s requirement rather than importing VIQUA’s number. This creates a potential pattern such as: **pressure tank → chemistry-specific pretreatment → softener if needed → model-required sediment polishing → UV → treated whole-house branch or point-of-use stage** But the pattern is only valid when the manuals and lab support it. A carbon tank might need a prefilter to protect its distributor. A softener might need protection from iron or sediment. A UV unit might need a defined turbidity, UV transmittance, flow limit, sample tap, and fail-closed valve. A point-of-use reverse-osmosis system may need a feed pressure range and drain connection that the whole-house train does not provide. ### UV is a final-polish constraint, not a universal final answer VIQUA’s manual says the UV unit’s installation depends on the specific flow rate, provides sample valves to confirm the water entering and leaving the chamber, and requires clearance for lamp and sleeve removal. It also requires a GFCI-protected controller outlet. The manual describes a flow restrictor as keeping flow within the maximum certified rate so an adequate UV dose is maintained. [Those are model-specific installation conditions](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf). The question to ask is not “Is UV last?” It is: 1. Is the UV after every pretreatment stage the manual requires? 2. Is the highest possible simultaneous flow at or below the unit’s certified flow under the stated water-quality conditions? 3. Will a clogged prefilter, bypass, alarm, no-power condition, or failed sensor stop or clearly flag water use? 4. Is there a sample point that distinguishes raw water, pretreated water, and final treated water? 5. Does the bypass send water to fixtures that the homeowner believes are protected? CDC’s scope is important here: UV with prefiltration can address parasites, bacteria, and viruses under appropriate conditions, but it does not remove chemicals. [CDC’s UV description](https://www.cdc.gov/drinking-water/about/about-home-water-treatment-systems.html) is why a UV lamp cannot be used to close a nitrate, solvent, pesticide, fuel, or metal gap. {{visual:pretreatment-and-uv-stack}} ### When two manuals appear to disagree Do not resolve a conflict by choosing the more familiar diagram. First check whether the devices are talking about the same thing. A manufacturer may say “prefilter” and mean a nominal sediment cartridge immediately before its UV chamber. Another may say “sediment filter” and mean a coarse protective screen upstream of a media tank. One manual may show a service bypass while another requires a fail-closed solenoid when disinfection cannot be assured. Those statements can coexist because they control different hazards. Use this review sequence: 1. Identify the exact model, revision, and configuration, including sensors, solenoids, flow restrictors, and optional cartridges. 2. Copy the manual’s requirement into the worksheet’s “manual-specific exception” cell, then translate it into a plumbing location. 3. Check whether another unit changes the condition. A softener, oxidizer, carbon tank, or pH stage can change particle loading, pH, temperature, chemistry, or flow. 4. Ask the manufacturer or qualified designer for a written answer when both requirements still cannot be met. 5. Do not delete a protective stage merely to make the drawing linear. If the proposal needs a parallel branch, sample valve, check valve, interlock, or separate treatment point, show it. The strongest answer is often “these two devices cannot share the same untreated or bypassed branch without a redesign.” A manual-specific exception should be visible to the homeowner and installer, not buried in a verbal explanation. ## 5. Check the hydraulic, drain, electrical, and bypass consequences A treatment train can have a plausible water order and still fail as a home system because one stage consumes the pressure or has nowhere safe to discharge. ### Compare service flow and pressure drop Collect the rated service flow and pressure drop for each stage. Pentair’s PC600-P and PC1000-P filter manual, for example, lists 8 and 12 gpm rated service flow and 13 psi pressure drop at rated flow for those models. [Pentair’s specification table](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf) is an example of the fields a quote should disclose, not a promise that your pump or house can deliver those flows. For a first-pass worksheet, use: **available pressure at the treatment inlet − pressure drop of every in-service stage − elevation and piping losses = pressure available at the critical fixture** Do not add a stage because its rated flow is “close enough.” If the quoted chain has a cartridge, carbon tank, softener, UV, and long small-diameter piping, ask for the pressure at the required peak flow with each stage in service. The weakest stage, not the average, controls the result. Also calculate the simultaneous event that is often omitted: a backwash or regeneration cycle while another fixture is open. If a backwashing media tank or softener must use a specified drain flow, the well pump, pressure tank, drain, and septic arrangement must support that event. If the control system prevents simultaneous cycles, the sequence and interlock should be written down. ### A practical pressure-and-flow audit The homeowner can assemble the inputs; a qualified professional should make any pressure-control, pump, electrical, or pressurized-plumbing change. Use this sequence when comparing two quotes: 1. **Set the demand case.** Write down the fixtures that might run together: a shower, toilet refill, washing machine, outside hose, or high-flow appliance. Do not accept “average household flow” without seeing the assumed fixtures. 2. **Identify the source case.** Record the well pump, pressure-tank size if known, pressure-switch settings if already documented, storage tank, booster pump, and any constant-pressure control. If a value is unknown, mark it unknown rather than substituting a typical number. 3. **List in-service losses.** Collect the clean and loaded pressure-drop information for cartridges and the rated-flow pressure drop for tanks, softeners, and UV equipment. The Pentair filter manual’s 13 psi at rated flow is a useful reminder that a named stage can consume a meaningful part of the pressure budget; it is not a value to copy to another model. [Use the proposed model’s own table](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf). 4. **List the limiting flow.** Put the lowest required service flow and the highest expected simultaneous demand side by side. For UV, use the certified maximum at the specified dose and water-quality condition, not a marketing number from a larger family member. VIQUA publishes flow by model and dose condition and describes a flow restrictor for maintaining the certified limit. [See the VIQUA flow section](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf). 5. **Audit the regeneration event.** Add the backwash, rinse, regeneration, or reject flow and state whether another device may run at the same time. If the controls prohibit overlap, the quote should say how that lockout works and what the household receives during the cycle. 6. **Check the critical fixture.** Identify the fixture that must still work: a shower, boiler makeup, or drinking-water branch. The final pressure number belongs at that fixture under the selected demand case, not only at the wellhead. 7. **Mark the measurement owner.** A homeowner can provide observations and existing gauge readings. A professional should verify dynamic flow, pressure behavior, pump controls, relief protection, pipe sizing, and any modification that can expose someone to energized or pressurized equipment. This procedure catches an attractive but misleading installation. A quote can show five units with individually acceptable ratings while the combined chain leaves too little pressure during a peak draw, or while a backwash cycle has no adequate drain. It can also reveal that the treatment order is acceptable for the main house but not for an outside branch or point-of-use membrane. ### Route every drain and protect every branch Pentair’s softener manual requires a drain line to an appropriate drain and warns about a filter and softener installed together. It prefers separate drain lines to the termination point because filter drain water can backfeed through the softener and overfill the brine tank. It gives alternatives if the lines must be joined. [Read the manufacturer’s drain guidance](https://www.pentair.com/content/dam/extranet/web/nam/pentair/manuals/37297-whole-house-water-softener-iom.pdf). Ask the quote to show: - each unit’s drain connection and expected flow; - the termination point and any air gap; - whether drain lines share a tee, and where any backflow protection sits; - whether the septic system, floor drain, dry well, or other destination is appropriate under local requirements; - whether chlorinated, salty, carbon-fines, iron, or chemical-containing discharge needs special handling; and - what happens if two units regenerate or backwash at once. An outside-faucet bypass can be deliberate, but it must be labeled. Pentair’s filter manual notes that its carbon system conditions the main supply while outside pipes may remain unfiltered. That may be reasonable for irrigation, but it changes the answer to “is every faucet treated?” [See the Pentair whole-house filter layout](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf). ### Power is part of the water path UV controllers, solenoid valves, alarms, softener controls, and chemical feed systems need power arrangements that match their manuals. The VIQUA manual requires a GFCI-protected outlet and describes a solenoid option that can shut off water when proper disinfection cannot be assured. [Use the exact manual and a qualified electrician for the electrical design](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf). Do not open energized controls, test live wiring, create a jumper, defeat a UV alarm, or connect a generator improvisationally. Do not assume that a powered display proves adequate dose, flow, pretreatment, or downstream protection. {{visual:flow-pressure-and-drain-check}} ## 6. Use this homeowner treatment-train worksheet Copy this table into the quote review. One row is one proposed device, including a cartridge housing, bypass, pump-related device, or point-of-use branch. | Stage and exact model | Lab purpose or claimed reduction | Required upstream protection | Min / rated service flow and pressure | Backwash, regeneration, drain, or reject | Power and access | Sample point | Bypass branch and what it serves | Manual-specific exception or unresolved question | |---|---|---|---|---|---|---|---|---| | Pressure tank / control boundary | | | | | | Raw-water sample? | | Where is pressure switch relative to restriction? | | Sediment cartridge | | | | | | | | Loaded pressure-drop trigger? | | Media or iron filter | | | | | | | | Backwash flow and cycle lockout? | | Softener | | | | | | | | Hardness, drain flow, outside-faucet branch? | | Carbon tank | | | | | | | | Claim, capacity, rinse or backwash? | | UV | | | | | | | | Flow limit, UVT, alarm, GFCI, final sample? | | Point-of-use stage | | | | | | | | Which outlet is actually protected? | Mark each cell **documented**, **measured**, **not applicable**, or **open**. “Open” is not a failure of the project; it is a reason not to approve a permanent plumbing change yet. {{visual:quote-review-worksheet}} ### Trace one drop of water through every branch After filling the rows, trace the drawing from source to fixture. Start at the pressure tank and follow the normal-service arrow through each stage. Then trace each bypass arrow separately. For each branch, answer three questions: - Does this branch receive the treatment the household believes it receives? - Does the sample tap prove the water at that branch, or only water somewhere else in the train? - If a stage is isolated for service, where can water go and what warning prevents it from being used as treated drinking water? This matters because a treatment train is often not one line. Outside faucets may intentionally remain untreated. A kitchen reverse-osmosis faucet may have its own prefilter and drain. A refrigerator may be connected downstream of a point-of-use cartridge but upstream of a whole-house UV unit. A bypass around a UV chamber may supply emergency water, but it can also make an ordinary valve position look like normal service. The drawing should label each branch **treated**, **raw**, **conditioned only**, **drinking point-of-use**, or **unknown**. Sample points should answer a question. A raw-water sample helps compare source chemistry with treated water. A pre-UV sample can show whether the UV’s required pretreatment is present. A post-UV sample can support verification of the treated branch, but it cannot prove that an untested chemical was removed. A point-of-use sample represents that faucet’s branch, not every fixture. Ask the laboratory or health department which sample points and analytes make sense for the decision; do not use a convenient tap as a substitute for the required sampling plan. {{visual:bypass-and-sample-branches}} The worksheet is complete only when the homeowner can explain what happens in normal service, maintenance bypass, power loss, alarm, and regeneration. If the answer changes between those states, put the state on the drawing. A future owner or service person should not have to infer it from valve handles. ### The five-gate review Approve a proposed order for professional design review only when all five gates are closed: - **Chemistry gate:** every stage has a named purpose tied to a lab result, a documented health or taste goal, or a manufacturer-required protection function. - **Pressure gate:** no cartridge or restriction undermines the pressure-control arrangement; the weakest-stage pressure drop and peak flow are documented. - **Treatment gate:** UV and other final stages receive the pretreatment, water quality, flow, and power conditions their exact manuals require. - **Discharge gate:** every backwash, regeneration, rinse, reject, and emergency flush has a routed destination and any required air gap or backflow control. - **Integrity gate:** every bypass, outside branch, sample tap, alarm, and service valve is shown so the homeowner can tell treated from untreated water. If one gate is open, ask for the missing manual page, lab result, flow calculation, drain detail, or branch label before plumbing is changed. ## 7. Know what to ask the professional—and what not to do yourself Bring the installer or treatment professional a complete packet: - the laboratory report and sample-point description; - the pump, pressure tank, pressure switch, storage, booster, and treatment model numbers; - the proposed flow and pressure assumptions; - the last 12 months of filter, salt, media, lamp, and chemical service records if available; - a simple fixture and branch map, including outside faucets and point-of-use devices; - the worksheet with every unresolved cell marked; and - the local health department or laboratory advice if the water is microbiologically unsafe, of unknown quality, or recently changed. Pentair’s filter manual says to check applicable plumbing, building, and electrical codes and not to use the system with microbiologically unsafe or unknown-quality water without adequate disinfection before or after the system. Its [softener manual](https://www.pentair.com/content/dam/extranet/web/nam/pentair/manuals/37297-whole-house-water-softener-iom.pdf) likewise directs installation under applicable state and local laws and regulations. [These are installation boundaries, not a national code summary](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf). CDC says to contact the health department or a well-water contractor to determine the best treatment option, and if harmful germs or chemicals are suspected, not to drink the water until treatment and follow-up testing show it worked. [Use CDC’s well-water treatment guidance](https://www.cdc.gov/drinking-water/safety/guidelines-for-treating-well-water.html). ### Exceptions that should stop a stock sketch Several system features can make a familiar pressure-tank-to-UV sketch incomplete. They are not automatic reasons to reject a project; they are reasons to redraw and verify the design. **A cistern or storage tank.** The pump that fills a storage tank may not be the pump that supplies the house. The tank can introduce a second pressure boundary, a booster pump, a float control, and a different source-water sample point. Ask whether treatment is intended before storage, after storage, or on the pressurized house line. A cartridge that is safe after the house pressure tank is not automatically safe between a fill pump and a storage tank. **A booster pump or constant-pressure system.** A manufacturer may use “after the pressure tank” to mean after the pressure boundary for that product. A booster can change where pressure is measured and how a restriction affects controls. Pentair’s filter manual specifically says to install following a booster pump when one is used; that is a model-specific instruction worth putting beside the actual pump arrangement, not a reason to move every filter after every pump. [Read the Pentair placement language](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf). **A shared well or multiple homes.** The homeowner may not control the full source, pump cycle, pressure, sampling plan, or treatment branch. Confirm ownership, responsibility, and the intended treated point before accepting a quote written as if the property had a private standalone well. **A treatment-only branch.** If only the kitchen or a drinking-water faucet is treated, the shower and ice maker may be outside the treatment boundary. That may be intentional, but the quote and labels must say so. A UV unit on one branch is not whole-house protection, and a point-of-use filter is not a reason to skip whole-house pretreatment when other equipment requires it. **A power-dependent germ barrier.** A UV, chlorinator, or control valve can change status when power fails. Ask what the water path does when the controller is unpowered, the lamp alarms, a sensor fails, or a solenoid is not energized. A bypass that supplies water during maintenance can be useful and still need a lock, label, alarm, or operating procedure. Never defeat an alarm or manually force a valve without the exact manual’s safe procedure. **A treatment stage that creates waste.** Backwashing media, softeners, carbon systems, reverse osmosis, and chemical feed can all create different discharge or maintenance requirements depending on the model. The drain is part of the design, not a cleanup detail. If the proposal says “connect to nearby drain,” ask what flow, air gap, backflow protection, local-code condition, and simultaneous-cycle assumption that phrase hides. **A changing water source.** Seasonal turbidity, drought, flooding, nearby construction, agricultural activity, or a repaired well component can make an old lab report a poor design input. EPA recommends immediate testing after a significant nearby change, a well-system repair or replacement, or a water-quality change. [Use the current EPA trigger list](https://www.epa.gov/privatewells/protect-your-homes-water). Do not preserve an old treatment order by treating new water as if it were the old sample. When one of these exceptions applies, the safest next step is a revised drawing with source, pressure boundaries, branches, sample points, drains, power, and failure states. If the installer cannot show the changed boundary, the homeowner cannot meaningfully approve the order. For a homeowner, the safe scope is observation and documentation: read labels, photograph accessible piping, record the model and revision, identify visible valves, and note which fixtures are on each branch. Assign energized electrical work, pressure-control changes, pump work, well opening, pressurized plumbing modifications, chemical feed, backwash-drain construction, and any confined-space entry to qualified professionals. Never open energized controls, test live wiring, open a well, pull a pump, enter a well pit, or manipulate pressurized equipment merely to confirm the proposed order. The finished decision is not “sediment, softener, carbon, UV.” It is a documented path from the tested water to the intended fixtures, with the pressure tank protected, each stage supplied within its manual limits, every waste stream routed, every bypass visible, and the final treatment claim matched to the contaminant it can actually address. That is the order worth approving. ## Evidence - [Boshart Industries — Can sediment filters be installed between the pump and pressure tank?](https://support.boshart.com/can-sediment-filters-be-installed-between-the-pump-and-pressure-tank) — Boshart’s explanation for this pump, filter, pressure-switch arrangement. It is not a national plumbing code and does not decide the placement of every engineered pretreatment device. - [Pentair — PC600-P / PC1000-P Whole House Water Filter System Installation and Owner’s Manual](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf) — The installation boundary for the named Pentair filter models. It supports a manual-specific placement check, not a universal sequence for all filters or wells. - [Pentair — PC600-P / PC1000-P Whole House Water Filter System Installation and Owner’s Manual](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf) — The listed specifications apply only to the named models and laboratory or manufacturer conditions; they are examples of fields to collect, not a sizing result for another system. - [VIQUA — D4 Premium, E4, F4 and related UV Systems Installation and Operation Manual](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf) — A model-family manufacturer manual. The 5-micron and after-softener requirement must be checked against the exact UV model proposed. - [VIQUA — D4 Premium, E4, F4 and related UV Systems Installation and Operation Manual](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf) — Installation and maintenance requirements for the named VIQUA models. Electrical work and any local-code interpretation remain professional and jurisdiction-specific. - [VIQUA — D4 Premium, E4, F4 and related UV Systems Installation and Operation Manual](https://viqua.com/wp-content/uploads/MNL520351-R_RevE-EN.pdf) — The dose, UVT, and flow figures are model- and condition-specific. They do not prove that a different UV unit treats a home’s peak demand. - [Pentair — Whole House Water Softening System Installation and Owner’s Manual](https://www.pentair.com/content/dam/extranet/web/nam/pentair/manuals/37297-whole-house-water-softener-iom.pdf) — Pentair’s installation guidance for the named softener system. Air gaps and drains remain subject to the applicable plumbing code and the exact equipment manual. - [Pentair — Whole House Water Softening System Installation and Owner’s Manual](https://www.pentair.com/content/dam/extranet/web/nam/pentair/manuals/37297-whole-house-water-softener-iom.pdf) — Specifications for the named Pentair softener models. They illustrate the worksheet fields and cannot be substituted for the proposed model’s data. - [U.S. EPA — Protect Your Home’s Water](https://www.epa.gov/privatewells/protect-your-homes-water) — General EPA private-well guidance. It does not select a treatment train or establish a universal contaminant panel for every well. - [CDC — About Home Water Treatment Systems](https://www.cdc.gov/drinking-water/about/about-home-water-treatment-systems.html) — General CDC treatment-scope guidance. It does not certify a particular UV model, flow rate, lamp dose, or chemical-removal claim. - [CDC — Guidelines for Treating Well Water](https://www.cdc.gov/drinking-water/safety/guidelines-for-treating-well-water.html) — General CDC guidance for suspected or confirmed well-water contamination. It does not provide a universal equipment order or replace local health-department advice. - [Pentair — PC600-P / PC1000-P Whole House Water Filter System Installation and Owner’s Manual](https://www.pentair.com/content/dam/extranet/nam/filtration/pentair/manuals/4006016-pc600-p-pc1000-p-system-manual.pdf) — Manufacturer safety and installation instructions for the named products. The article does not turn them into national code or licensing claims.