A brand new home should not leak, and it is frustrating when one does. But new builds are put together quickly, by many different trades, with modern plastic pipework and sealed boxing that hides most of the plumbing. Small installation faults are not unusual, and they often take weeks or months to show, once the home is lived in and the heating has been running.
This guide covers where new build leaks tend to start, how to tell a plumbing leak from the other kinds of water a new home can suffer, how builder warranties generally work, and how to document the problem so the developer can act on it.
Why do new build houses leak?
Most new build leaks come down to installation rather than worn-out materials. The common threads are:
- Speed and sequence. Plumbers, dry liners, tilers and kitchen fitters follow each other closely, and one trade can damage another's work without knowing.
- Hidden pipework. Pipes run in floor voids, stud walls and boxing that are closed up soon after first fix.
- Push-fit plastic systems. They are quick and reliable when fitted correctly, but a pipe not fully inserted, cut unevenly or missing its insert can hold for a while and then weep.
- Settling and drying. New buildings dry out and move slightly in their first year, which can stress seals around baths and showers.
- Systems that are not used straight away. A fault on a heating circuit or a spare bathroom may not show until those parts are used regularly.
Where do leaks usually start in a new build?
| Location | Typical fault | What you might notice |
|---|---|---|
| Push-fit joints in floors and walls | Pipe not fully inserted, damaged O-ring, missing pipe insert | Ceiling stain below, damp skirting, meter moving with everything off |
| Walls and floors after fitting-out | A screw or nail through a hidden pipe from a skirting, shelf, radiator bracket or kitchen unit | Damp directly around a fixing, sometimes appearing weeks after the fixing went in |
| Showers and baths | Waste not tightened, silicone gaps, tray not fully supported | Ceiling stain below the bathroom after use |
| Toilets | Pan connector not seated, cistern seals or inlet connection | Water around the base of the pan, stain below |
| Underfloor heating | Loose manifold connection, damaged loop from later work | Falling pressure, damp near the manifold cupboard |
| Boiler, cylinder and airing cupboard | Compression joints not fully tightened, relief valve discharging | Water on the cupboard floor, boiler pressure dropping |
| Kitchen | Sink waste, appliance hoses and valves, dishwasher connection | Swollen plinths or cabinet bases, lifting flooring |
If you are curious how plastic and copper pipework compare, our guide to plastic and copper pipe leak risk covers the differences.
Is it a plumbing leak or something else?
New homes can be wet for reasons that have nothing to do with pipes, and it is worth separating them before contacting the developer, because the investigation is different.
- Construction moisture. Screed, plaster and concrete hold a lot of water when new and release it over months. This shows as general condensation and damp that is spread out, not concentrated at one point.
- Condensation. Modern homes are airtight. Without enough ventilation, moisture from cooking, showers and drying clothes settles on cold surfaces, especially windows and corners.
- Water getting in from outside. Rain through windows, balconies, roofs or badly finished external details tends to appear after wet weather.
- A plumbing leak. Damp concentrated around a fitting or pipe route, that grows whether or not it has rained, or a water meter that moves with everything turned off.
A simple meter test is the quickest way to check the supply side. With every tap, appliance and toilet off, read the meter, wait at least half an hour without using water, and read it again. Movement means water is going somewhere.
How do new build warranties generally handle leaks?
Most new homes in the UK come with a warranty from a provider such as NHBC, and the details vary between providers and policies, so your own policy document is the one to rely on. Under NHBC's Buildmark cover, the first two years after legal completion are a builder warranty period, during which the builder is responsible for putting right defects that come from its failure to meet NHBC's requirements. NHBC asks homeowners to contact the builder as soon as they reasonably can, and always within that period. Its resolution service is available if the builder's own complaints process does not resolve the matter. From the third year, the cover changes to insurance for specific types of damage, with narrower scope.
The practical points that apply to most warranties are:
- report the defect to the developer in writing, as soon as you notice it;
- give the developer the chance to investigate and repair;
- keep a record of every contact, visit and response;
- check your policy before arranging and paying for your own repairs, as the developer may expect to investigate first.
If the leak is causing damage right now, protect your home first: isolate the water, contain it and make electrics safe. Then report it.
How should you document a new build leak for the developer?
- Write down when it started. The date you first noticed the damp or stain, and when it seems to get worse, such as after showers or when the heating runs.
- Photograph it regularly. The same view each time, with the date, so the growth of a stain is clear.
- Mark the edge. A faint pencil line around a damp patch, with the date beside it, shows whether it is spreading.
- Record meter and pressure readings. Meter readings with all water off, and boiler or underfloor heating pressure readings taken cold at the same time each day.
- Note what you have done. Any valve you have closed, any appliance you have stopped using.
- Report in writing. Use the developer's customer care process, attach your photos and readings, and keep a copy.
- Keep everything together. Emails, visit dates, names of the people who attended and what they said.
This record helps the developer find the fault quickly and helps you if the matter has to be escalated.
What can you check yourself in a new build?
A few simple checks help you give the developer useful information without opening anything up.
- Find your stopcock and valves. In new homes the stopcock is often under the kitchen sink or in a utility cupboard. Check that it turns and that the taps stop when it is closed. Many new bathrooms and kitchens also have small isolation valves on the pipes to each toilet, basin and appliance.
- Watch the pressure gauges. Read the boiler gauge, and the underfloor heating manifold gauge if there is one, with the system cold at the same time each day.
- Look behind access panels. Bath panels, boxing with removable covers and the manifold cupboard can show a wet pipe or joint directly.
- Isolate one outlet at a time. If damp appears below a bathroom, closing the isolation valves to one fitting and watching whether the damp stops growing helps narrow it down.
- Stop using a suspect fitting. If a shower or bath seems to be the cause, avoid using it until it has been checked.
Avoid drilling, cutting or lifting anything to look for the leak. Opening up a new home yourself can complicate the developer's investigation and your warranty position.
What if the developer cannot find the leak?
This happens, particularly with intermittent leaks or pipework buried in screed. If a visit has not found the source and the damp is still growing, an independent leak detection survey can help. The engineer uses pressure testing to confirm which circuit is losing water, then thermal imaging, acoustic listening or tracer gas to locate it, and records the findings in a written report. That report gives the developer a precise location to work from. Before commissioning one, check with the developer and your warranty provider how they will treat an independent report.
When should you call a leak detection specialist?
- the developer's visit has not found the cause and the damp continues;
- the meter moves with everything off and nothing is visible;
- underfloor heating or a sealed heating system keeps losing pressure;
- you need an independent, documented location before any floor or wall is opened.
A combined detection package is £250 to £500, and under-floor leak detection is £300 to £700. Our underfloor heating leak detection page explains how loops are tested. See our water leak detection service, or call 020 3912 0200.
Frequently asked questions
Is it normal for a new build to leak?
It is not what anyone expects, but small installation faults are not unusual in new homes. Report any leak to the developer promptly so it can be put right.
Who fixes a leak in a new build house?
In the early years, usually the developer, under the builder warranty period set out in your warranty policy. Check your own policy document for the exact terms and time limits.
How do I know if it is a leak or drying-out moisture?
Drying-out moisture and condensation tend to be spread across the home and worse in cold corners. A leak is usually concentrated around a fitting or pipe route and grows over time. A meter test helps confirm a supply leak.
Should I get my own plumber to fix a new build leak?
For an emergency, stop the water and make the home safe. Before arranging your own repair, check with the developer and your warranty terms, as they may expect to investigate and repair the defect themselves.
Can a leak detection survey help with a developer dispute?
An independent report gives a documented location and cause where they can be established. How it is used in any dispute depends on your warranty terms and the developer's process.
