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Stop Taps Guide – Internal & External

Stop Taps

What are Stop Taps?

Stop taps do exactly what they say, they are taps, levers or valves that (when turned off) stop the flow of water to a property. Knowing where both your internal and external stop taps are is extremely beneficial when you have a water leak because you can shut off the flow of water to your house, potentially helping to reduce the water damage from a water leak.

They are also extremely useful during the process of water leak detection to help understand where the leak is. For example, is it a supply pipe water leak or an internal water leak? If it is an external water leak we have a useful guide on who is responsible for a water leak outside and another guide on how to report a water leak, both of which include this useful diagram.

Report a Water Leak
Who is Responsible for a Water Leak?

Even if you do not currently have a water leak, knowing where your internal and external stop taps are is useful information for when you need it. If you don’t know where they are check now as they could help prevent water leak damage at your home or business.

Remember also that some properties will have more than one internal stop tap to isolate the water in different parts of the house. Knowing where these are is useful too. The same goes for isolation valves too (more on these later).

External Stop Taps

External stop taps are often found at the boundary box to a property. As the name suggests, this is often at the boundary of a property and is often where the water meter is too and is where people often come to read a water meter – see the diagram above for an example of this. A boundary box might look like this…

External Stop Tap
External Stop Tap Lid

If the water is turned off at the boundary box, both the property and supply pipe will be isolated from the mains water from your local water company. If you cannot find your boundary box, then speak to your local water company as they will likely have details to help you.

In some instances, external stop taps supply water to several properties, so it is important to be aware of that information!

Internal Stop Taps

Internal stop taps (remember there may be more that one) are usually the one that people will be most familiar as they will often be in a place where you’ll often see it in your property.

There is no single place where they will be in a property, however, they are usually at the side of the property where the mains water enters (for obvious reasons). Also, they will commonly be under a sink like this example…

Internal Stop Tap
Internal Stop Tap – with Water Leak Sensor

This particular stop tap has a smart water leak sensor attached to it, but you can see how the kitchen cupboard carcasses have been left with a cut-out on them to access the tap. It would be a problem if it had been boxed in and was inaccessible – this does happen sometimes.

We discuss internal stop taps in our informative article explaining the process of dealing with a water leak between home and water meter outside.

Stop Tap Problems

An issue when people have low water pressure is that their stop tap is restricting flow to the rest of the house. This isn’t a very common problem but it does happen. This can be measured with a water flow meter if you have one.

It is important to be careful with these taps because, as you might expect, they spend almost 100% of their usage lifetime in the open position not being moved regularly at all. This can mean that they get stiff or ceased up, making it difficult to move them. This is not an uncommon problem, especially in older properties. So always be careful, you do not want to break it and cause another leak!

This brings us onto another related subject…

Internal Stop Tap - Earthed
Internal Stop Tap – Earthed

Stop Tap Leaks

When people have a water leak at their property, it is sometimes the case that they actually have a leak in their actual tap and either the tap itself or the fittings around it need replacing. This can be caused by a number of reasons, but most commonly it is simply an old tap becoming perished. Another fairly common problem is a new one not being fitted correctly and then causing a leak.

As you might expect, this kind of leak can be a trickle or a dramatic gush / full mains pressure leak. This is certainly an instance when you need to know where your external stop tap is because you clearly cannot turn of your internal one if it is broken.

To understand how much water you can get with a leak, check out our water leak calculator.

Isolation Valves

In more modern properties, or if someone has had their plumbing updated by a local plumber (for example with a new bathroom) you commonly see isolation valves like the one below.

Isolation Valve
Isolation Valve

Isolation valves can be found on various places in properties, including on toilets and sinks etc. They exist to be able to isolate the water supply for the device. This is clearly handy when doing a water leak repair, fitting a new / replacement device following a leaky toilet or (you guessed it!) if you have a water leak at your home or business.

We discuss sink leaks in our article about Mr Muscle Drain Gel

Using the toilet isolation valve above as an example, you can see that there something that looks like a flat screw head. Notice how the line is aligned to the flow of water in the pipe. In most instances to turn of the water to an appliance using an isolation valve, that just needs turning 90 degrees to block the flow. It is usually a very quick and simple process and, again, useful to know.

We do sometimes get called out to a property in an emergency where something like a toilet has a major water leak with water gushing everywhere and the homeowner didn’t know that there was an isolation valve or stop tap. That can save a lot of water damage when you have a water leak in houses so make sure you know (a) if you have them (b) where they are and (c) how to open and close them in an emergency.

If you need help with a water leak contact us today. logo logo

Does a stop tap stop all water?

Internal Stop Tap - Earthed

Generally yes, assuming it is the only water feed to a home or business, switching a stop tap (or stopcock) off should stop all water to the property, unless it is broken or old, in which case it may let water through. Remember that some properties may have an internal and external stop tap so both can be utilised depending on the situation, or as a back-up to the other.

Do all houses have a stop tap?

Internal Stop Tap

It would be incorrect to say that all houses have an internal stop tap. However, nowadays most will have and many will have more than one. On top of that, isolation valves are increasingly common on modern fittings, which work in a similar way to a stop tap on a local area. Most houses should have an external stop tap (location will vary) that is generally the responsibility of the local water company if it is outside the boundary of your home or business.