one-way "valve" for toilet

[rpurcell21047]

I know they make something for a toilet that keeps waste from coming back up if the sewage backs up. Does anybody know exactly what it is called and how hard it is to install one. We are putting a bathroom in our basement and have a pump to pump the waste up and out of the house. My fear is if that pump doesn't come on, like it has once already, the sewage will come back out of the toilet.

[LazyPup]

The valve you are asking about is called a "Backflow preventer" however the code would prohibit installing one on the line from your water closet to the sewage ejector vessel.

Code does require that you install both a backflow preventer and a manually operated gate valve on the discharge riser from the sewage ejector pump.

Before you begin this project you better sharpen your pencil and do some careful calculations to determine if it is feasible for your house.

Under the International Residential Code the minimum rate of discharge from a sewage ejector pump must be 14.2 gallon per minute.

The drainage load must be computed at 1.5 DFU (drainage fixture units) for each gallon per minute.

Thus the minimum load from a sewage ejector pump must be computed at 1.5 x 14.2 = 21.3DFU.

You must first determine the DFU load that currently exists on the pipe and add the 21.3DFU to determine total load.

At a minimum a house must have one bathroom, a kitchen and a laundry standpipe. This means the minimum existing load would be as follows:

Water closet.(1.6gpf).......................3DFU

Tub/shower.................................... 2DFU

Lavatory........................................ 1DFU

Kitchen sink.................................... 2DFU

Laundry Standpipe........................... 2DFU

Total 10 FU

10DFU existing load + 21.3DFU from the ejector pump = 31.3 DFU.

A 3" branch line is limited to 20DFU so you would not be permitted to connect the pump discharge line to the branch.

A 3" house sewer and house main drain is limited to 36 DFU so you could connect your sewage ejector to a 3" main drain providing you do not already have a second bathroom in the house, otherwise you would need to change the entire main drain and house sewer line to 4".

[rpurcell21047]

Thank you for explaining everything. All are drains are in as well as the pump so am I to assume that when they installed the pump a backflow preventer was put on that. It sounds like there is not much I can do if the pump stops working. It does sound like that if there is a backflow preventer on the pump the only waste that would back up would be the waste that has yet to be pumped. I can take a little cleaning just don't want the whole basement to be flowing with waste.

Thanks for your help.

[LazyPup]

Whenever it is desired to install plumbing fixtures at a level below the gravity flow drain lines in a structure it is necessary to provide a means of lifting the generated waste up to the level of the gravity flow drains. In order to do so we use a "Sewage Ejector Pump Assembly".

Basically a sewage ejector pump is simply a variation of a sump pump. It has a receiver vessel installed at a level below the new fixtures so the effluent disharging from the fixture can flow to the sump by gravity flow in the conventional manner. Once the effluent collects in the sump it is then pumped up to a point where it can be discharged into the regular gravity flow drains of the structure.

The principle differences between a sump pump and a sewage ejector pump are:

1. The effluent collecting in a sewage ejector pit contain biodegradable materials that will produce sewer gasses as they decompose, therefore it is necessary to equip the pit with a water tight cover and provide a vent to atmosphere to discharge any sewer gasses produced in the pit.

2. While a sump pump is only designed to discharge water, a sewage ejector must be capable of discharging both water and any contained solid particulates. This can be achieved in one of two manners. Either the pump is a "Trash pump" that has an impellar designed to handle solid waste or the pump is equiped with a "Macerator/grinder" which grinds the solids into small particles that can pass through the pump.

Normally a sewage ejector is installed below floor level and the top of the pit will have a watertight cover that has a removable access hatch to permit servicing the pump. It will also have two pipes, one for the vent and the second pipe is the discharge line from the pump.

The discharge line from the pump is required to rise vertically to the point of attachment with the structure gravity flow drains. There must be a "Backflow Preventer" on that line and above the backflow preventer you must have a manually controlled gate valve. The backflow preventer will prevent any sanitary waste in the higher gravity flow line from backflowing into the sewage ejector pit.

The manual gate valve is required to permit manually closing the line in the event it becomes necessary to service either the backflow preventer or the pump.

The vertical discharge line from the pump must rise to a point higher than the gravity flow line to which it discharges then drop back down and connect to the gravity flow line by means of a WYE connector with the side opening of the WYE on the top of the horizontal gravity flow line to which it is connected. The WYE must also be connected so it directs the flow in the downstream direction on the gravity flow line.

[rpurcell21047]

Thank you for explaining once again. What you describe is exactly what they put in so I feel better about it. We will have a plumber connect the drain pipes for us anyway but now I know where we need to put access panels when putting up the drywall.

Thanks again.