Plumbing problems

Some basins have no overflow arrangements, and a trap blockage can have devastating results. You can easily fill up baths and basins to check overflows.

Tap connectors are well hidden under baths and sinks, and commonly leak. It is not difficult to understand why. If you have ever worked under the tap end of a bath you will be aware of the twists and contortions your body will need to be forced into to make and tighten or untighten connections. Special basin spanners are manufactured to help plumbers here.

Working in tight situations behind a basin pedestal is also challenging. Tap connections are usually made using 15mm tap connectors for basins, and 22mm for bath taps. Onto the tap connector, either soldered or spannered onto the pipe feeds – you slip a fibrous washer. To the inexperienced this is a potential leak waiting to happen – over-tightening the tap connector nut onto the threaded tail of the tap can damage the rather weak fibrous washer material (in effect, munching and shredding it into oblivion). Experience and care are needed – and a little plumber's boss white to help make a good seal to the tap. A dry finger will pick up any drip here once the water supply to the tap is activated.

Figure 1:  Tap connections, options 1–3 (left–right)

Option 1 (see figure 1) is a crinkly copper tube with a standard housing at the business end for a fibrous washer; this could save time bending tube or fitting countless elbow fittings under a bath or basin.

Option 2 can sometimes fail. Within the metal braiding is a rubber hose that can split under stress. Floods have resulted from poor fitting of this kind of flexible connector. However, the rubber washer produces a very reliable seal from connector to threaded tap tail.

Option 3 is a standard copper tube terminated by an end feed soldered tap connector. It is sealed to the tap using a fibrous washer. The tube nearly always needs to be bent. This is achieved easily using a professional pipe bender. If the pipe is bent too quickly, it creates ripples on the inner side of the bend. Check bath tap connections if you can. A bath panel with an inspection door, or a panel that could be removed, helps.

There is a limit to how many times cheap fittings can be tightened and untightened.

On most baths there is a plastic imitation metal overflow fitting with the circular holes (imagine too the cheap plastic crinkly overflow tubing, that simply push fits onto the downward-pointing spigot). The crinkly pipe will also be push-fitted to a fitting above the bath 'P' trap. Such an overflow system will not have the capacity to deal with a bath that is seriously filling up from both taps turned on. The bath water level will just keep rising until it overflows onto the bathroom floor. The real test is to turn on both hot and cold taps, fit the plug in the bath, sit back and observe. As the water level gradually rises up the side of the bath, the bath of course gets heavier and heavier. If the bath is acrylic it might flex, putting considerable strain on the edge seals – and once the water begins to gurgle through the overflow outlet, do not be one bit surprised if the water level continues to rise until you finally decide to turn the taps off. Overflow pipes will rarely cope with a full-blown rise in the bath water but would just deal with a less serious escape, such as getting into a bath which has been filled too high.

Figure 2: Basin waste fittings. The slotted waste on the left is brass with chrome plating. It is bedded into the basin using plumber’s mate and the threads sealed using, for example, hessian and boss white. It is not easy to seal the threads, but this must be done or there will be a leak. The easy option is to fit a plastic waste that seals under the basin – just tighten it up and there will never be a drip problem. The integral overflow will be located above the fitting and there is no need for a slot in the waste

Figure 3: Sitting in the bath, you would observe such an overflow fitting, to which the plug is attached. You are looking at a sham: not chromed metal but just cheap plastic

Because the overflow pipe enters the waste system above the trap connection, if the bath trap is blocked, so too is the overflow. The potential for flood damage is obvious, as you can see from figure 4.

Figure 4: Bath overflow

Figure 4 shows bath overflow. To the left you can see where overflow travels – out of the bath high up via the overflow fitting, down the crinkly pipe and into a black plastic fitting to which the bath 'P' trap fits underneath.

An overflow should really be serviced by a separate pipe that bypasses the trap – and should really not even be linked to the same waste pipework system. Such an overflow pipe just needs to exit through an external wall and ideally feed down to a yard gully, where its splashing outpouring can be spotted.

Basins commonly leak underneath, where waste fittings have been poorly installed.

Frequently, kitchen and basin traps can be found completely mummified by all manner of tapings and bandagings. Such an approach can never cure a leak. Plumbing fittings need to be taken apart, carefully inspected for flaws, cleaned, washers and seals replaced if need be, and reassembled. Not an expensive or difficult job for a householder to tackle – and straightforward for a plumber.

Bathrooms and showers: good design practice

Figure 5: This is the ultimate solution if a bath is to be used for showering. A hinged glass panel creates in effect a shower cubicle on 3 sides. The 8mm toughened glass door features an anti-drip channel. Showering tests the quality of tiling and seals to the bath, which need to be of the highest standard. Image © courtesy of Matki Showering, www.matki.co.uk

Figure 6: This shower tray is fitted into a purpose-made shower enclosure, and is fitted with a dedicated shower trap for good flow performance. Special fastflow wastes can cope with 30 litres of water per minute. Image © courtesy of Matki Showering, www.matki.co.uk

Figure 7: Here is a great design solution: a shower tray with a removable front panel for access and maintenance, which is also designed to be aesthetically pleasing – no clumsy or unsightly screws or brackets. Image © courtesy of Matki Showering, www.matki.co.uk

Figure 8 : Shower trays Sketch © courtesy Matki Showering

On the left of figure 8 is a shower tray with an integral upstand, which makes it easier to achieve a perfect perimeter seal. The right-hand tray may also be installed to produce a good edge seal, but may fail if the tray is able to flex or is not supported properly underneath. Remember that seals have an expected life, and need to be periodically checked and occasionally re-run.

Silicone seals should completely fill up the junction of upstand, walling and tiling with silicone. Success cannot be achieved with just a single gunned line of sealant applied after tiling.