Sizing Sump Pump Output Pipe

[MikePA]

We have two, small sump pump pits in our basement, however only one of them has a pump in it. The output pipe is 1.25" rigid, plastic pipe. It comes up out of the pit where I have a joint so I can lift the assembly out of the pit if I have to. Above this joint, the pipe continues to the joists, where it makes a 90 degree turn, goes across the basement, where it makes another 90 degree turn (right above the second pit) and heads out the sidewall.

I want to put a pump in the other pit and tie it into the existing output pipe (if possible).

My concern is whether the existing 1.25 inch pipe could handle the output of 2 sump pumps should they come on at the same time.

Can they?

[BrianP]

Although you can probably put all the water you want through a 1.25 in pipe, you should probably step up to a 1.5 inch pipe. Although it can only carry about 45% more water, the drag & all should make up the difference. Make the change after the second pump.

Don't forget that you will need directional valves (one way) on the sumps, or you will end up just pumping the water from one pit to the other.

[wingnut]

<font color="blue"> or you will end up just pumping the water from one pit to the other.
</font color>
and that's the other alternative ... which is what I did. I had a big pump already in the main "pit" so I just added a smaller one in the sub-pit and moved the water over.
If you have too much water coming in, that might not work .... but if you have that much water coming in .... you've got a bigger problem than pipe sizing!

[Inspector507]

Just put in check valves and don't worry that water will get into another pit.