In this project we’ll show you how to find the source of any water leaks around your house, going through all the different potential sources of water in your house to make your water leak detection an easy process.
The visual signs of the water leak are great indicators for where the leak is, whether it’s water coming through walls or water in your basement, so we cover these too so that you can properly identify where your leak is coming from.
Use a Damp Meter to Locate the Area Affected by the Water Leak
If you think that you may have a water leak based on the fact that you have some damp or cold areas on your wall, you should confirm that these areas are damp or cold.
There are a number of tools available to help you with this, such as a surface thermometer or damp meter – these can also be useful if you’re not sure where all of the affected areas are.
If you can’t get hold of one of these devices just use the back of your hand to detect colder or damper areas of your wall, floor or ceiling.
A damp meter does what it says on the tin – you stick its prongs into your wall and it tests the wall for dampness.
You can also use a hygrometer – this tests the moisture content of the air in your room, and is useful for determining whether condensation is the real cause of your damp patches rather than a water leak behind or in your wall.
Water Leak Detection Checklist
1. Leaking Mains Supply
The leak may be coming from your water mains supply, or there may be a mains water leak from your neighbour’s property.
A leaking water main further up the road also could cause any leakage into your basement that you may be experiencing.
You can contact your water supplier and get them to check your mains supply and your neighbours’ supply – the only neighbour’s that can really affect you are those either side of you or those on higher ground than you.
2. Test Water
If water has come through your walls or floor or into your basement you can get your water supplier to test it to determine where it’s come from.
They will be able to tell you whether it’s ground water, mains water or sewage.
You can find your local water supplier on Water UK’s website
3. Leaking Foul Water Pipes
You can test whether your foul water pipes have any leaks by blocking them up.
Find out where your foul water drains away by turning a tap on and lifting up your manhole cover.
You can block the hole the water flows from into the manhole with a bung available in either 4 inch or 6 inch sizes from your local builders’ merchants.
Fill up your toilet bowl or sink with water and mark the level of the water. Leave the water overnight and see what happens.
If the level of the water has dropped overnight then you need to get a drains company to come in to investigate and trace the leak in your pipes.
You can find a qualified company to do this on the National Association of Drainage Contractors website.
Alternatively, you may have a pretty good idea of where the leak is coming from at this point if you know where your wet area is, so you will know what needs to be mended. Make sure you remove the bung after completing the test!
4. Using Dye to Test for Leaks
You can check whether the leak is coming from a fault in your surface drain by using a bag of drains testing dye that you can buy from your local builders’ merchants.
Put the dye in the drain and then fill the drain up with water. This dye glows in the dark so you can then look at your leak at night and look for the dye to confirm that the water is coming from your surface drain.
5. Check Fittings and Appliances
If the water is leaking in to your actual bathroom or kitchen it’s a good idea to check your plumbed in appliances and bathtub/shower cubicle, sink and toilet.
Water within an actual room is normally the cause of a leaking appliance (washing machine, dishwasher etc.) or fixture such as bath, shower enclosure or the similar.
When the appliance is running or the fixture is in use, check all around them thoroughly and confirm that there are no leaks present.
6. Check Central Heating System
If the water is appearing in your floor you should check your central heating system as this may be the source of the leak.
Check your pipes and radiators, with your first check being the pipes that run under the area of damp floor.
You can also ask a plumber in to do a pressure test as this may help to trace where in the system the leak is coming from if this is the source of the leak.
If you can’t find any leaks but you still have damp and cold patches of wall, these may be being caused by damp rather than a leak.
Take a look at our Diagnosing Damp project to work out what kind of damp may be affecting your walls.
After Tracing the Source of Water leaks and Fixing Them
Once you have traced the source of the water leak in your home and repaired it so that it no longer poses any threat, the next job is to then repair the damage that it’s caused.
This often means repairing or replacing damaged plaster, paint work, wallpaper etc.
Are There Any Black Mould Patches on Walls or Ceilings That Were Exposed to the Water Leak?
You’ll probably have to strip off all the plaster in the mould affected area right back to the wall.
Allow the wall to dry fully and treat the wall with an Anti-Moulder Cleaner and killer to remove any remaining spores.
After you’ve used the cleaner and allowed it to dry you can then replaster. To be totally sure that your mould won’t return you can use special Anti-Mould paint that you can add to your own paint, as well as an Anti-Mould additive for wallpaper paste.
Have you got White, Crunchy Crystals in your Plaster Damaging Paint and Wallpaper?
These are ‘salts’ that have been washed out of your brickwork by the water from your leak, meaning that they’re now present in your wall’s surface. What you have to do to fix this really depends on the state of your plaster.
If it’s sound then you can simply strip any decoration off, leave the wall to dry, treat the plaster with Salt Neutraliser and once that’s dry redecorate.
It is, however, likely that the salts have blown your plaster. You can tell if this has happened by whether the plaster is coming away or it sounds hollow when you tap it.
If this is the case, you’ll have to strip the plaster back to the wall underneath and then leave the wall to dry, and once it is, again treat it with a Salt Neutraliser.
You can get salt neutraliser that you paint directly onto your wall’s surface, or a salt neutraliser that you can add to your plaster mix for replastering.
If you directly paint on the neutraliser, when it is dry you can then replaster and redecorate.
If you have a serious salt issue you can take an extra measure to prevent salts appearing in your plaster. This involves adding a mesh membrane to your wall before replastering over the top of the membrane. More information on fitting a mesh membrane to your wall can be found in our Mesh Membrane Project.
If you have a leak in your home it is highly important that you find the source and fix it as if you don’t this can lead to a whole host of other more expensive and more in-depth issues.