Every water treatment unit has a few places where it can leak: the supply tie-in, the drain connection, the valve fittings, the housing seals, and the tank itself. When an installer sets the unit, the question of who pays if one of those connections fails later is easy to skip. It matters more than most features on the spec sheet, because a slow leak behind a cabinet can soak a subfloor or drywall long before anyone notices.

Ask for a certificate, not a verbal assurance

Ask the installer for a current certificate of insurance that shows general liability coverage, and ask whether they carry workers' compensation if they have employees. The statement that they are insured tells you nothing about the limits or whether the policy is active on the day they work in your home. Check that the certificate names the business that will actually do the work. If the installer uses a subcontractor for the water line connection, ask for that subcontractor's certificate as well.

Confirm who is licensed for the connection

Plumbing work is regulated at the city or county level, and the rules differ from one jurisdiction to another. Ask who will make the supply and drain connections, what license that person holds for your address, and for the license number so you can verify it with the issuing office yourself. Then ask who is responsible if the connection fails. The answer should name a company, not just a technician, so that you know who to call and who has to pay.

Find out what your own policy covers

Call your homeowner's insurance agent and ask two plain questions. First, does the policy cover water damage that starts from a water line or appliance inside the home? Second, are there exclusions or sublimits for leaks from equipment installed by a contractor? Coverage depends on the specific policy and insurer, so get the answer in writing or by email rather than relying on memory. If your policy covers the damage, ask what your deductible would be for that kind of claim. If it does not, you know to press the installer harder on their liability coverage before you sign anything.

Put the damage terms in the quote

Ask the installer to state in writing who repairs water damage caused by a leak at the new connections, how long that responsibility lasts, and how you report a problem. Ask whether this is separate from the equipment warranty. A warranty that covers the unit does not automatically cover your floor, cabinets, or wall finishes. Confirm whether the installer will pay to open up and replace finished surfaces to reach a leak, or only the cost of the part that failed. If the answer is vague, get the vague answer in writing too, so you can compare it with other quotes.

Document the space before the crew starts

Take time-stamped photos of the floor, the wall behind the install area, the cabinet base if there is one, and the existing shutoff valves before work begins. Note where the main shutoff is and make sure everyone in the household knows how to close it. If there is already staining or a soft spot, photograph it and point it out to the installer. These photos settle disagreements later about what was there before the work started.

What to do with the answers

Before you sign, you should be able to answer four things: which company carries the liability, whether that company's coverage is current, what your own policy will pay for, and who repairs the surfaces if a connection fails. If the installer cannot produce a certificate or will not state the damage terms in writing, treat that as the answer and compare another quote. A lower price does not make up for an unclear claim path after the water is already on the floor.