A slow draining shower is almost certainly due to either a drainage blockage or possibly a shower tray and its plumbing fittings not being correctly angled. Needless to say, blockages should be fairly easy to rectify and clear to get the shower draining properly, so too should showers with a tray. But having to sort out a slow draining shower in a wet-room - will be a more difficult undertaking.
Causes of Shower Blockages
You need to remember the shower is for taking a shower in, drying yourself off and then stepping out of it. If you stand their using cotton-buds, tissues, face-mask packs etc - you need to be careful that you don’t create debris that can get washed into the shower drain.
Avoiding hair getting into the drain is pretty well impossible to do, but other than that it should only be soapy water going down there. If for some reason you have no drain hole cover, then the blockage may well be due to all manner of debris blocking the plumbing. So, once you’ve cleared the blockage get a new drainhole cover fitted, to prevent the problem recurring in a few weeks time.
Clearing Slow Draining Shower Blockages
If the slow drainage is due to a blockage then, if you’re lucky, you might be able to clear it without getting at the trap underneath. First off try using a plunger to suck the debris causing the blockage out, if that fails try pouring drain blockage solvents down. These will probably need leaving for 24 hours to maximize their effectiveness.
If that doesn’t work, then you need to remove the side panel of the shower tray that gives you access to the shallow seal trap. If you can maneuver a shallow tray under it do so, otherwise put some old rags/towels underneath to mop up the inevitable spillage.
Unscrew the trap and clean thoroughly with a flexible brush, also clean down the outlet piping that connects to the trap. You’ll probably be able to judge by the amount of material that comes out of these components if a blockage was the problem causing the slow draining shower.
If water is backed up to the wastepipe, then the blockage is further away from the shower tray. So you’ll then need to locate the next trap fitting in the plumbing and repeat the operation, until you locate the blockage. This is unlikely to be the main out-side drain, as you’d experience other drainage issues in your plumbing.
Slow Shower Drainage Problems
If there is no blockage in the shower tray plumbing then the problem is most likely the angle that the tray is sitting at or the angles of the plumbing fittings. Fortunately, the shower tray will have adjustable feet, by removing he shower tray inspection panel you should be able to re-angle the shower tray so that the waste water can more easily flow down the drain hole.
You should also be able to make adjustments to the feet which will raise and lower the plumbing fittings, without having to completely remove them, so that the waste water is able to more easily drain away. As the height/position of the tray will have been changed, you might then need to re-seal the tray to the floor and walls with some fresh caulk.
For a slow draining shower in a wet-room, the procedures to follow are the same as those just described for a shower tray. However, in the case of a wet-room you’ll be working through an inspection cover in the floor of the wet-room, which simply makes everything more difficult. Also, there’s no easy way to adjust drainage angles and to avoid having to re-tile the whole floor to get a better slope - you’ll have to re-fit, re-angling as you go, the plumbing fittings if there’s no blockage.
Photo by Makuahine Pa’i Ki’i, Creative Commons Attribution