swimming pool construction London


17 June 2014
My pool might be leaking

If you suspect that your swimming pool has a leak, early detection is paramount in order to avoid more complicated issues further down the road. A leaking pool can result in hundreds of gallons of water being lost every day. More seriously, it can cause severe structural damage to the pool itself and to other buildings nearby.  A leak doesn’t have to be big for there to be a huge loss of water; a miniscule hole can be an even worse problem because it’s much harder to find.  Fortunately, if you do suspect you have a leak; it’s easy to get the problem resolved before any significant damage is done.


Check the filter multi port valve: A lot of suspected leaks can be attributed to the Multi Port valve on the swimming pool filter. If your pool is losing water it is possible that the culprit is the gasket in the multi-port valve. If it has worn it will not be creating a positive seal between the ports of the valve and it can allow a small amount of water to pass out through the waste port. This would not be visible unless you were to disconnect the waste pipe connection to the multi-port valve. The remedy is to call your pool professional to come and replace the spider gasket in the valve or replace the whole valve if that is not possible. Also installing a valve on the waste pipe is a good idea, however always ensure you open it when either backwashing or emptying the pool.

The bucket test: While any noticeable loss of water in a short space of time (eg one day) is a key indicator that you may have a leak, if you have an outdoor pool and the weather has been particularly warm, the problem might simply be evaporation. The quickest and most inexpensive way to determine whether you have a leak is to do a bucket test, as demonstrated in this video. Place a bucket filled with pool water on the step of your pool and weigh it down with a rock. Mark the water levels both inside and outside the bucket (they should be the same) at the start of the test and then again seven days later. If the water line has dropped more outside the bucket than inside, this is evidence of a leak.

Inspect the pool liner: If you have a liner pool, look for cracks and tears around the lights, skimmer, returns and suction line.  Testing the liner thoroughly could involve being underwater for a period of time in order to examine the underside of the liner meticulously.  For this work, we recommend that you use a professional pool servicing company.  Pool liners are not invulnerable and they do suffer from wear and tear if they have been in place for several years. In older pool liners, tiny holes sometimes occur which are difficult to detect. The liner fabric can often become damaged around the corners and steps of the pool, so pay close attention to these areas.

Beware the smaller cracks: In a concrete pool, tiles can come loose or can fall off entirely, causing obvious leakages. However, smaller cracks in the walls and floor are often harder to find. Again this may require some time underwater in order to examine these areas closely and your professional pool servicing company will be able to assist. Often with concrete pools, leakages occur due to inadequate sealing, poor structural design or the usage of inferior concrete, so structural enhancements will need to be made in order to solve the problem in the long run.

Suspicious air bubbles: Leaks in the pool’s suction lines may not result in severe water loss in the same way that a crack in the wall or floor will, but such a leak can cause significant damage to the pool’s plumbing system. If you see air bubbles in the water in the return line when the pump is running, this indicates a leak in the suction line. Likewise, air bubbles in the return line may also be the result of blockages in the suction line.  Carefully inspect all connections, seals, gaskets and o-rings.


If you’ve determined that your pool has a leak, whether or not you’ve found the precise culprit, it’s important that you get in touch with your local pool professionals immediately to get some advice. LSPC’s engineers are highly trained to the standards of the Institute of Swimming Pool Engineers and are equipped to identify and deal with all kinds of leakages, from tiny cracks in the wall to more comprehensive structural problems. Remember; don’t delay fixing the problem because the damage can get exponentially worse the longer you leave it!

At London Swimming Pool Company we specialise in swimming pool maintenance, servicing and refurbishment, so if you have a pool that’s in need of regular maintenance or a facelift, contact us for an initial discussion – there’s no substitute for expert advice. If you have an older swimming pool that needs upgrading, we suggest planning your refurbishment for the autumn, so all the work is done and dusted before the next swimming season.

Photo: Meltingdog

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