Bathtub Drain Vent

All the faucets and water appliances in a house use this same system of drains pipes and vents.

Bathtub drain vent. As water goes down a drain air is needed to equalize the pressure in the drain line. Here is a tub drain pipe and partial vent system. Drain pipes take the wastewater to the soil stack. This pic shows the main outlet to the septic.

There is also a wet vent but these are mostly reserved for tubs that sit close to a stack and may not be allowed by your locality s code. Drain and vent lines must be positioned precisely so you should install them before the supply pipes. Directly above it is the wc. The pipe with the black tape coming from the right is for the bathroom sink drain.

It loops up an around before connecting to the drain pipe allowing ample ventilation to take place just behind your fixture. If reventing is difficult and wet venting isn t allowed you may have to install a separate vent pipe through the roof. This is the purpose of a venting system. Without venting the negative pressure caused by the flow of draining water can potentially suck water out of the drain trap and allow sewer gases to enter the home.

Its purpose is to equalize pressure in the pipes and prevent a vacuum from forming as the fixture drains. This is what the average bathtub drain and vent system looks like if you could remove the drywall or plaster from your walls. It may be possible to simplify supply runs by moving a vent pipe over a few inches. The loop vent is a solution for many freestanding sink codes.

If the drain lines in your home have poor venting as in figure a for example water rushing down the drains will pull water from nearby p traps. A good drain waste and vent layout takes bathroom laundry room and kitchen configuration into consideration when planning where the main vent and soil stack is located and how each drain and. If you must run drainpipes across a floor carefully calculate the amount of vertical space available. Through the stack sewer gases are carried up to the roof through vent lines.

The plastic pipe connected to the tub is the overflow pipe. For a freestanding sink code may allow a loop vent. You must slope the drainpipe at 1 8 to 1 4 inch drop per foot. The same holds true for plumbing vent pipe.

So the additional slope of just 1 8 inch per foot reduces the allowable drain length between the trap and vent by a whopping 2 66 feet or 33. Keep the vent connection above the trap weir when i m performing a plumbing inspection i don t often bother with measuring the exact drain length unless it seems to be unusually long or is clearly at a shallow slope. The pvc angling up is the 2 vent stack through the roof. The combined bathtub and kitchen drains enter on the opposite side behind in the pic of the cast iron.

Water enters it and flows down into the.