A water treatment installation is not complete just because the equipment is connected and water is flowing. Before making final payment, compare the finished job with the written agreement and collect the records you may need for service, warranty claims or a future home sale.

This is not about looking for excuses to delay payment. It is about confirming that both sides agree on what was installed, what remains unfinished and who is responsible for the next step.

Start with the signed agreement

Bring the signed proposal, contract and approved change orders to the final walkthrough. Do not rely on the salesperson's summary or your memory of the conversation.

Read the documents once for equipment and once for labor. Check whether the agreement identifies:

  • The type of treatment system
  • The manufacturer and exact model number
  • The size or rated capacity
  • Each included tank, control valve, filter, faucet, pump or accessory
  • The plumbing areas the system is supposed to serve
  • Included removal or disposal of old equipment
  • Electrical, drain and plumbing work
  • Startup, testing and homeowner instruction
  • The amount due at completion

If the paperwork uses general phrases such as complete system or standard installation, ask the company to identify exactly what those phrases covered. A vague scope is harder to compare with the finished job.

Match the installed equipment to the paperwork

Find the product labels on the control head, storage tank, filter housing, membrane assembly or other major components. Compare the model information with the signed agreement.

Record model and serial numbers before labels become dirty, blocked or difficult to reach. Photographs are useful, but also request a written equipment list from the installer. If a tank and its control valve have separate identifying numbers, record both.

Ask about any difference you find. A substitution may be reasonable when a specified component is unavailable, but the company should explain the difference and document your acceptance. Confirm that the replacement is compatible with the rest of the system and that it does not reduce promised capacity, functions or coverage.

Confirm the installation scope room by room

Walk through every area affected by the project. Follow the path from the main water line to the treatment equipment, then check the fixtures or branches that were supposed to receive treated water.

Look for contract items that are easy to overlook, including a bypass valve, shutoff access, drain connection, air gap, dedicated faucet, leak protection device, pressure regulator or electrical outlet. Confirm that abandoned tubing, packaging and replaced equipment were handled as promised.

If wall, cabinet or floor openings were required, compare the repair work with the contract. Some companies include basic sealing or cleanup but exclude finish carpentry, painting, tile work or drywall repair. The written scope should settle who is responsible.

Ask for the startup record

The installer should be able to explain how the system was started and configured. The appropriate record depends on the equipment, but it may include programmed settings, measured water conditions, flow direction, filter flushing or confirmation that the drain cycle operates correctly.

For equipment with an adjustable control, ask the installer to show you the current settings and explain which ones a homeowner should not change without guidance. Write them down or photograph the display. If a future power interruption resets the controller, this record can prevent guesswork.

If the contract promised post-installation testing, obtain the result in writing. Check that the tested locations and reported measurements correspond to the promise. A verbal statement that the water looks good is not a substitute for a required test result.

Test normal operation during the walkthrough

Ask the installer to demonstrate the equipment instead of only pointing out its location. You should know how to:

  • Use the bypass valve
  • Shut off water to the system
  • Recognize a normal operating display
  • Identify the drain line and confirm where it discharges
  • Check consumable levels when applicable
  • Respond to a leak, alarm or loss of pressure
  • Find the company contact information for service

Run water at representative fixtures while checking accessible connections for dripping. Listen while the equipment operates. Ask which sounds are expected and which ones should prompt a service call.

Do not dismantle equipment or attempt tests that create a safety risk. The purpose is to observe normal operation and receive a practical handoff from the installer.

Separate unfinished work from future maintenance

A final invoice may arrive while a minor task is still open. Put every unfinished item in writing, even if the installer has already promised to return.

A useful completion note identifies the specific task, the person responsible and how completion will be confirmed. Avoid broad notes such as finish later. Write something concrete, such as secure drain tubing at the utility sink or provide the missing filter wrench.

Do not confuse unfinished installation work with scheduled maintenance. Replacing a consumable after normal use is different from providing a part that should have been included at installation. Ask the company to label each item clearly.

Collect the documents that stay with the system

Before closing out the project, request a complete handoff packet. Depending on the installation, it may contain:

  • The signed contract and all approved revisions
  • The final invoice showing payments and balance
  • An itemized list of installed equipment
  • Model and serial numbers
  • Owner manuals
  • Written operating settings
  • Startup or test records promised in the contract
  • Warranty registration confirmation when registration is required
  • Service contact information
  • Maintenance instructions and consumable specifications
  • Permit or inspection records when the job required them
  • Receipts or acknowledgments for removed rental equipment when relevant

Store the packet near other home records, not on top of the equipment where moisture can damage it. Keep a digital copy of the most important pages and equipment labels.

Read the final invoice before paying

Compare the final invoice with the contract total, deposit, approved additions and credits. Ask about any new line item that does not appear in the signed documents.

Check how the invoice describes the equipment. A clear description is more useful than a generic line such as water system. Confirm that the payment amount and accepted payment method match the agreement.

If something is disputed, describe the exact mismatch in writing and ask the company to respond. Keep the discussion focused on the contract language, installed components and observable work. Review your agreement before changing or withholding a payment that it says is due.

Get completion acknowledged by both sides

Some contracts include a completion certificate or customer acceptance form. Read it before signing. Determine whether it only confirms installation or also states that every part of the work is satisfactory and complete.

Do not sign a statement that conflicts with the condition of the job. If a minor item remains open, ask whether it can be listed directly on the form or on an attached punch list acknowledged by both parties.

Keep the final paid invoice or receipt. It should show that the account balance is zero once all required payments have been processed.

Use the paperwork to evaluate the handoff

A strong installation handoff should leave you able to identify the equipment, operate the basic controls, understand routine upkeep and prove what the company installed. Missing paperwork does not automatically mean the system is defective, but it can make later service and responsibility questions harder to resolve.

If you still need to choose a provider, the Best Water Companies STL award winners page offers a starting point. You can also review the award methodology to understand how companies are evaluated. No matter which company you select, keep the written scope beside you from installation through final payment.