Bathroom Plumbing Terms


Shut Off Valve | Pressure-Balancing Valve | Thermostatic Valve| P-Trap | Vent Stack | Main Stack

Although you may not need to know the details, you should be familiar with the terms. Understanding these may save you money, improve your safety and prevent problems in the future.

Shut Off Valves

In a bathroom emergency, you may need to know how and where to turn off the fixtures that use water. Right below the tank for the toilet is where you usually find the water valve for the toilet. It is near where the water pipe comes through the wall and has a small, silver, football-shaped handle on it. If your toilet looks like it may overflow, close the shutoff valve and it will stop the water flow. Look under the sink for its shutoff valves.

Pressure-Balancing Valve

If you have young children or elderly people living in your home, this valve may be important to you. It is required by most building codes. Found in most new shower faucets and sink faucets, a pressure-balancing valve is the standard type of anti-scald device installed. It automatically maintains the water temperature if there is a change in the supply pressure and will prevent you from being scalded in the shower if someone flushes the toilet or from being hit by a blast of cold water if someone turns on the washing machine.

Thermostatic Valve

Like a pressure-balancing valve, a thermostatic valve has the same purpose, but it uses a thermostat-controlled device to mix the precise amount of hot and cold water to maintain consistent water temperature without affecting the flow rate. To prevent scald prevention, they can be used on individual faucets or can be installed on the outlet side of a hot water heater to protect the whole house.


Under the sink, is the P-trap. It is the U-shaped section of drain pipe under the sink. Hopefully, you won’t ever need to do this, but if you drop your wedding ring or something important down the sink drain, check the P-trap. To remove it, loosen the big slip nut at each end of the trap. Don’t forget to put a bucket underneath first because it will be full of disgusting water. You can also do this if your sink is having trouble draining. Clean out the trap and the sections it is connected to or you can call us if you need a plumber.

Vent Stack and Main Stack

Do you know the difference between a vent stack, soil stack, main stack or main drain? A stack is a vertical pipe. The main stack is the large, 4-inch pipe which runs from the basement, up through the house, and ends about a foot above the roof. The drain lines feed into the main stack, and then become the main drain located in the basement or crawlspace, and lead to your septic tank or city sewer line. The soil stack is the section of the main stack used for draining waste.

Call Emory Garland Plumbing for all of your plumbing needs.