When it comes to installing drains, size matters. The recommended pipe size for a shower drain is 2 inches, whereas most tubs use 1.5-inch pipes. Why the difference? Shower pans are shallower than tubs, so there's a higher risk for overflow.
Especially with today's 2-1/2 gallon per minute shower heads, an 1-1/2'' pipe will easily carry the flow, and, in fact, will give a better scouring action than 2'' pipe in such low-flow conditions.
According to the Universal Plumbing Code, the standard drain size for a washing machine is 2 inches. The absolute minimum should be about 1 1/2 inches. However, keep in mind that wash load capacities can vary by up to 400% or more depending on the model.
The minimum size drain for a shower with more than one 2.0 G.P.M shower head which may operate simultaneously shall be two inches. Multiple shower heads which operate simultaneously up to and including ten G.P.M shall have a minimum two-inch drain.
Furthermore, you can snake a 1 1/2 in. drain. I thought back to that one job more than 40 years ago when my father sat me down and explained that a shower drain only needs to be 1 1/2 in. If you make it 2 in., you will constantly have stoppages.
Shower drains shall have an outlet size of not less than 11/2 inches (38 mm) in diameter. Waste fittings shall conform to ASME A112. 18.2/CSA B125.
But do you know the proper slope? The ideal slope of any drain line is ¼ inch per foot of pipe. In other words, for every foot the pipe travels horizontally, it should be dropping ¼ inch vertically. Many drains either have too little slope or too much slope.
The interpretation of this slope is that as x increases by 1 y will increase by 1.5. So we can say that tanθ = 1.5/1 =1.5. arctan1. 5= 56.3°. The angle that corresponds to a slope of 1.5 is 56.3 degrees.
Pitch on a sewer line for a building or home
In the cases of a 6″ sewer line the minimum recommended pitch on a sewer line is 1/4″ per foot, or about one foot for a fifty-foot run.
The drain pipe should be a minimum of 1-1/2" I.D. (inside diameter) to ensure proper draining. The Washer drain hose is a 1-1/4" O.D. (outside diameter). To be confident that no siphoning of water will take place, the drain plumbing must be a minimum of 30" high for Top Load Washers.
Yes, with a Y-fitting, you can successfully connect a utility sink and washing machine to the same drain.
Install a P Trap
A P trap is a necessary part of the plumbing for a washer. It's a U-shaped piece of piping between the appliance and the sewer line. After water drains out of the washer, the P trap's shape holds enough water to create a barrier between the house and the sewer line.
Basically a standard tub drain is 1.5". The trap and drain needs to be that size or more. A standard shower drain is 2". The trap and drain needs to be that size or more.
All pipes in your home, particularly for toilets, sinks, and showers, require proper venting. It protects the trap on the drain pipe. In addition, it helps you secure your wallet, fittings, time, and even the pipe itself.
A bath tub drain shall be a minimum of 2 (horizontal) or 1 ½ (vertical) drain pipe size, with a minimum 1 1/2 vent pipe size. A lavatory requires a 1 ¼ minimum drain and vent pipe size. The minimum slope required for drainage piping less than 4 in pipe size is ¼ per foot slope.
Pipes must slope slightly downhill to drain properly. The standard slope is anywhere from ¼ inch to 3 inches per foot depending on the use.
For optimal water drainage, it's advisable to ensure that the shower floor maintains a gentle gradient of approximately 2-4 percent. This corresponds to a decline of ¼ to ½ inch for every 12 inches from the shower enclosure to the drain.
Note: The industry standard for shower slopes is a range of 1/4″ to 1/2″ per foot.
In a stall shower, the plumbing code requires the floor to be sloped one quarter (1/4) of an inch per foot in order to carry the water effectively to the drain.
Keep in mind that shower drain assemblies are generally made to fit a 2-inch drainpipe, not the 1 1/2-inch pipe usually found on tubs. A 2-inch pipe is the recommended size because showers have a low threshold for flooding, and a 2-inch pipe helps the water drain faster than does a 1 1/2-inch pipe.
A high flow rate showerhead will require a larger drain size to handle the volume of water being produced. Some common standard shower drain sizes in the industry include 1-1/2 inch and 2-inch drains.
A 32mm waste pipe is typically used for appliances that present low volumes of water to the system (e.g. small hand basins), while 40mm is normally used for kitchen sinks, showers and baths. 50mm, on the other hand, is large to suit commercial applications or connect multiple waste pipes to a single flowing system.