A slow drip from an ordinary overflow pipe is usually not an emergency, but it is a sign that something needs fixing soon. It becomes more urgent if the flow is heavy, the overflow is blocked or water is coming into your home. Water from a hot water cylinder’s safety pipe is a different matter and needs prompt professional help.
When a Dripping Overflow Can Wait a Little
Most overflow drips come from a toilet cistern or a cold water cistern in the loft. The overflow pipe is there to carry extra water safely outside, so a slow drip means the system is working as designed.
In this case, you usually have time to arrange a visit at a sensible time. It is still worth acting within a few days. A small leak can grow, it wastes water, and in cold weather a constant drip may freeze and cause icy patches outside.
Signs It Needs Urgent Attention
Some overflow problems need faster action. A heavy, continuous flow from the pipe suggests the valve may have failed badly, and the cistern could struggle to keep up.
A blocked or frozen overflow is another concern. If water cannot escape through the pipe, the cistern may fill until it spills over the top. In a loft, this can lead to water coming through the ceiling below.
If you see bulging plaster, spreading stains or water dripping from a ceiling, treat it as urgent. If it is safe and you know where it is, turn off the stopcock to slow the flow. Keep clear of any wet light fittings or switches and get an electrician to check them.
A Cylinder Safety Pipe Is Different
Not every pipe that drips outside is a cistern overflow. Homes with an unvented hot water cylinder have a safety discharge pipe. This often runs through a small open funnel called a tundish, then out to a drain or an outside wall.
Water or steam from this pipe can signal a fault with the cylinder’s safety controls. It should never be blocked or capped, as it is designed to release pressure safely. Keep well away from any hot water or steam, and contact an appropriately qualified professional urgently.
If the cylinder or boiler is involved, follow the advice of the qualified engineer who attends. Do not try to adjust or repair any part of an unvented system yourself.
Getting the Right Help
If you are unsure what kind of pipe is dripping, look at where it comes from. A pipe from the loft or a toilet is usually a cistern overflow, while a pipe near the airing cupboard may be linked to the cylinder.
For ordinary cistern overflows, a plumber can find the cause and fix the valve. You can learn more about help with a leaking overflow pipe on our service page. If you are worried about water damage, our emergency plumbing page explains what to do next.
If you are not sure how urgent your overflow problem is, Emergency Plumber Swindon can talk it through and take a look at the plumbing side. Call 01793 569521 for friendly advice in Swindon.