The weird and wonderful workings of taps

Tap Innards - The weird and wonderful workings of taps.

Now I know what you're thinking, why would I need to know about the workings of my tap? Well if for example your tap seizes up or starts dripping most people think "oh the tap has had it I better go out and buy a new one" we hear this so often when serving customers and they would of ended up buying a complete new tap when they could of repaired their original.

If you know how your tap works then you can more easily explain to a plumber what the problem is so they can fix it or if you are a DIYer fix it yourself.

Number one: Original washer valves

Washer valves operate on a thread so when you turn the tap head it raises and lowers a brass stem with a washer on the bottom to control the flow of water.

Old taps used to have rising head valves that operated on a single thread and the head would rise up when you turn it on and fall when turning off. A very durable type of valve, one that manufacturers have all but done away with nowadays which is a shame.

Modern valves are operated on a worm-screw thread with a male thread going in to a female thread operating a plunger (for the use of a better word) that has the washer on the bottom.

The most common type of problem with these is seizing. Over time the constant water pressure will push the threads causing them to dig in to each other. In this case you would need to replace the valve

Another problem is dripping from the spout. The rubber washer on the bottom of the valve perishes or goes hard so won't do much when you want to turn the water off! In this case take the valve out and put a new washer on (these are normally a few pence down your local hardware shop).

Replacement washer valves can be found here

Number two: Splined ceramic disc cartridges

These are most common nowadays because they are easy to turn on a off. They have two pieces of ceramic in them: one that is fixed in the bottom and another that slides over the top of it. Quarter turn cartridges have two triangle sections cut on each disc, when these two line up it allows water to pass through. 

Half turn cartridges are the same except with a half moon shape cut out.

Now the problem with these are that they can scratch, if a tiny piece of grit or dirt gets between the two discs it will scratch them and let enough water through to cause a drip.

Also over time with the discs being moved over each other so many times they wear grooves in to each other which then again allows water to pass and cause a drip.

The easiest way to fix this is to replace the cartridge but there lies another problem, there are a great deal of variation on the market. These differ in the number of grooves around the top to the overall height, so do be careful when looking for replacement cartridges.

Replacement ceramic disc cartridges can be found here

Number three: Joystick ceramic cartridges

Found in single lever taps and as the title would suggest they are operated on a joystick stem which like the splined cartridges move ceramic discs over each other.

Most cartridges have three holes, two are for the hot and cold water and the third is to let water in to the tap.

When you lift the tap head you are moving the discs so the hot and cold water holes open allows water flow in to the cartridge and out in to the tap.

Moving the head left and right will allow more hot or cold water by opening up the preferred hot or cold hole and closing the opposite hole.

The problems that occur with these are the same as the splined cartridges, they scratch or wear grooves in to themselves. On the rare occasion the joystick can snap off.

Replacement cartridges can be found here