A leaking water main is an emergency whether it’s inside your home or in your driveway. Water pressure is high (2-4 bar typical), water volume is huge (you can lose 40-80 litres a minute from a small hole), and damage compounds quickly.
Here’s what to do in the first 10 minutes, whose responsibility the pipe is (yours or NI Water’s), and what repair typically costs in Belfast.
First 10 minutes: stop the flow
- Find your stopcock and turn it off. In most Belfast homes this is:
- Under the kitchen sink
- In a cupboard near the front door
- Occasionally in an under-stairs cupboard
- Turn a cold tap on at the ground floor to drain residual pressure
- Move valuables away from the leak area
- Note the leak location (indoor / outdoor, visible / suspected)
- Ring us, or NI Water if the leak is in the street
If you can’t find the stopcock, turn off at the meter outside (small metal cover usually near the kerb, lift with a screwdriver).
Your responsibility vs NI Water’s
The dividing line is the external stopcock at your property boundary (usually near the kerb or front wall).
| Leak location | Whose responsibility |
|---|---|
| Inside the house | Yours |
| In your garden / driveway, between the external stopcock and the house | Yours |
| In the street, before the external stopcock | NI Water |
| Unclear location (wet ground near the boundary) | NI Water will investigate |
If you think it’s NI Water’s: ring them on 03457 440 088 (24 hours). They investigate free and repair free.
If it’s yours: it’s a private repair, typically £320-£1,400 depending on location and access.
Signs of a water main leak
Not all leaks are obvious:
- Hissing sound near the stopcock or along the wall where the pipe enters the house
- Damp patches on walls or floor near the mains entry point
- Water meter running when no taps are open (check the meter with everything off for 10 minutes)
- Unexplained high water bill
- Wet patch in the garden that doesn’t dry out
- Water pressure unexpectedly low at all taps
- Swampy or discoloured grass over the mains line
Typical repair cost (Belfast 2026)
| Scenario | Typical total |
|---|---|
| Mains leak at internal joint (under sink, in cupboard) | £180-£350 |
| Mains leak in the wall (accessible) | £280-£480 |
| Mains leak under a concrete floor (excavation required) | £480-£950 |
| Underground mains leak in garden (excavate and repair) | £380-£750 |
| Underground mains leak under driveway (excavate, re-lay, re-surface) | £750-£1,400 |
| Full mains replacement (boundary to house) | £950-£1,800 |
Prices include leak detection (if needed), repair, backfill, and basic make-good. Driveway re-laying or tarmac reinstatement is usually itemised separately.
Response times
- In-city Belfast, working hours: 2-4 hours
- Lisburn / Newtownabbey, working hours: 3-5 hours
- Bangor / Ballymena: 4-6 hours
- Out of hours emergency: up to next morning where safe to wait (if stopcock is off and no ongoing damage)
See Emergency Plumbing for the full service.
If the stopcock is seized
Common problem. The stopcock hasn’t been turned in 10+ years and won’t budge.
- Don’t force it with a wrench. Forcing a seized stopcock snaps the valve body and makes a small leak into a flood.
- Ring us, or NI Water, urgently. They can turn off at the external valve at the kerb.
We replace seized stopcocks as part of the repair call or as a preventive job (£95-£160 fitted).
Insurance
Most buildings insurance policies cover:
- Damage caused by the leak (walls, flooring, ceilings)
- Trace and access (the cost of finding the leak)
Most policies do NOT cover:
- The cost of the pipe repair itself
- Escape-of-water excesses (£100-£500 typical)
- Gradual damage if you knew about the leak and didn’t act
Always report a leak to insurance within 48 hours of discovery, even if you’re not claiming yet.
Prevention
- Exercise your stopcock every 6 months (turn it off and back on)
- Insulate the pipe where it enters the house (prevents freeze-thaw damage in winter)
- Keep an eye on your water meter reading monthly
- If your mains pipe is lead, plan for replacement: lead mains are a water quality issue and a leak risk. £950-£1,800 typical.
Book an emergency visit
For active leaks, phone is fastest. For non-urgent (suspected leak, high bill investigation) send photos and the location. We respond inside 2-4 hours in working hours.
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