Thread: sump pump discharge reduced to 3/4

I've never seen a sump pump discharge pipe reduced down to 3/4". That can't be right can it? Seems like it could reduce the life of the pump.

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I just had the exact thing come up last week and called it out for the reason you site.... I never researched it but I agree... it has to be wrong. I was in the crawl testing the pump and noticed it emptied the sump really slowly (and was a new pump). When I found the small discharge line it made sense.

I can't remember the flow rates right off the top of my head but I have to think a 3/4" line is about 1/10 the flow of a 2".

Well, one thing's for certain - the pump isn't going to move the volume it was designed to move.

it will work fine as long as they never get water
sometimes people just dont think

That looks like a sewage ejector system and if so the discharge piping must be 2” in diameter. UPC 710.2
If it’s just a below grade sump pump ¾” diameter piping is OK.

I had the very exact situation yesterday with standard sump pump draining 10 feet to the exterior. It was reduced with a gate valve at the reduction. Only drain water was being pumped, not any sewage. I would have defected the installation had it been anything other than gray water.

Originally Posted by William Zoller

I had the very exact situation yesterday with standard sump pump draining 10 feet to the exterior. It was reduced with a gate valve at the reduction. Only drain water was being pumped, not any sewage. I would have defected the installation had it been anything other than gray water.

It wasn't grey water, and its still wrong.

2006 IPC

SECTION 1113 SUMPS AND PUMPING SYSTEMS

1113.1 Pumping system.

The sump pump, pit and discharge piping shall conform to Sections 1113.1.1 through 1113.1.4.

1113.1.4 Piping.

Discharge piping shall meet the requirements of Section 1102.2, 1102.3 or 1102.4 and shall include a gate valve and a full flow check valve. Pipe and fittings shall be the same size as, or larger than, pump discharge tapping.

Exception: In one- and two-family dwellings, only a check valve shall be required, located on the discharge piping from the pump or ejector.



Note: the exception for 1- and 2-family dwellings does not except the size of discharge piping. That which continues beyond the check valve remains discharge piping.

The 2006 IRC refers one to IPC:

2006 IRC:
SECTION P2601 GENERAL

P2601.1 Scope.

The provisions of this chapter shall govern the installation of plumbing not specifically covered in other chapters applicable to plumbing systems. The installation of plumbing, appliances, equipment and systems not addressed by this code shall comply with the applicable provisions of the International Plumbing Code.

I had to guess location state since it wasn't provided, and could only think of one "Loveland". The UPC (CPC is based upon as well) requires similar as well despite assertions of others earlier.

Thanks H.G. Watson. I'll print that code and keep it handy.