Here is the short answer: a water leak detection system pairs small sensors under the risk points — sink, washing machine, boiler, bath — with a motorised valve on your mains stopcock, so a leak is detected in seconds and the water shuts off automatically. The Ajax WaterStop valve fits DN15 to DN25 pipework (that covers most UK homes), joins the same app as an Ajax alarm, and turns £4,000 of ceiling damage into a mop and a five-minute reset.
In brief:
- Escape of water is consistently among the most expensive and most common UK home insurance claims — and it usually happens while nobody is in.
- A leak sensor alone tells your phone; a sensor plus a motorised shut-off valve actually stops the water.
- The Ajax WaterStop comes in 1/2", 3/4" and 1" sizes and closes the mains automatically the moment a paired detector gets wet.
Burglary gets the attention; water does the damage. A failed washing machine hose or a weeping joint under the bath runs quietly for hours — through the ceiling, down the walls, into the electrics — and the average escape-of-water claim costs thousands and weeks of drying out. We have supplied Birmingham from Villa Road since 1975, and leak protection has quietly become the upgrade we recommend to more households than any camera.
How does a water leak detection system work?
Two parts. Detectors — small battery pucks that sit on the floor wherever water would first arrive: under the kitchen sink, behind the washing machine, in the boiler cupboard, beside the bath trap. And a shut-off valve fitted to the rising main, which closes itself the moment any detector reports water. Detection to closed valve takes seconds; the leak gets a puddle, not an afternoon.
Why is the valve the part that matters?
A sensor that only notifies your phone assumes you are awake, in signal, and twenty minutes from home. The 3am burst pipe and the leak that starts an hour into your holiday fail all three tests. The valve removes the assumption — the water stops whether or not anyone reads the alert. That is the difference between knowing about the flood and not having one.
The Ajax WaterStop DN15 (1/2") suits the 15mm pipework most UK homes carry at the stopcock, with the DN20 (3/4") and DN25 (1") covering larger mains — and the DN15–DN25 Jeweller model with its 8.5 N·m motor for the valve that has not been turned since the house was built. All wireless on Ajax's Jeweller radio, all controllable from the app: shut the water from the sofa, the office, or the departure lounge.
Trade tip: match the valve to the pipe size at the point you are fitting it — check before ordering, because "the stopcock under the sink" is 15mm in most houses and 22mm in plenty of others. And exercise any motorised valve monthly from the app; thirty seconds of movement keeps a valve free that limescale would otherwise seize.
Where should leak detectors go?
- Washing machine and dishwasher — hoses and their connections are the most common failure we hear about.
- Under the kitchen sink — traps, flexi tails and waste joints.
- The boiler and cylinder — pressure-relief drips become streams.
- Bathrooms — behind the bath panel and under the basin, where the slow leak lives longest unseen.
- Anywhere with history — the corner that stained once will stain again.
Ajax's LeaksProtect detectors are the pucks designed for exactly these spots and pair to the same hub and app as the WaterStop — browse the full Ajax range for the current line-up.
Does it work with an Ajax alarm?
Seamlessly — that is the design. The WaterStop enrols on the same Ajax hub as your intruder detection, so one app carries the burglar alarm, the fire detection and the water protection, with the same shared users and the same event history. If you are starting from nothing, an Ajax kit plus a WaterStop is the whole-house package; if the hub is already on the wall, the valve is an afternoon's addition.
Water Protection, Summarised
| Pipe at the stopcock | Valve | Price |
|---|---|---|
| 15mm (most UK homes) | WaterStop DN15 1/2" | £116.47 |
| 22mm | WaterStop DN20 3/4" | £130.11 |
| 28mm / larger mains | WaterStop DN25 1" | £172.01 |
| Stiff or aged valves, DN15–DN25 | WaterStop Jeweller 8.5 N·m | £151.79 |
Expert Help in the West Midlands
Villa Road, Birmingham, since 1975. Bring a photo of your stopcock and we will size the valve on the spot — and tell you honestly when the fitting is a competent-DIY job and when the state of the pipework says get a plumber in for the half hour. Fitting a valve to the mains is plumbing; if in doubt, a plumber fits it in under an hour and the wireless side needs no one at all.
Browse the Ajax range. Get in touch to size a system.
Related reading: which Ajax kit do you need and are Ajax alarms any good.
Frequently Asked Questions
Do water leak detectors really prevent damage?
Detectors alone shorten a leak; a detector paired with a motorised shut-off valve prevents most of the damage outright, because the mains closes in seconds whether or not anyone sees the alert. The valve is the half of the system that does the preventing.
What size WaterStop do I need?
Match the pipe where it will be fitted: DN15 for 15mm pipework (most UK homes), DN20 for 22mm, DN25 for 28mm. Check the pipe before ordering — it is a two-minute look with a tape measure.
Can I turn the water back on remotely?
Yes — the WaterStop opens and closes from the Ajax app, so after a false alarm or a fixed leak the mains comes back on from wherever you are.