Troubleshooting: When the Pump Is Pumping, But the Level Is Not Going Down

When you’re called out for a high water alarm and the pump appears to be working, follow these tips to diagnose the issue

Troubleshooting: When the Pump Is Pumping, But the Level Is Not Going Down

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When making a service call for a high water alarm activated at a customer’s house, we arrive to find the pump pumping, but the level in the tank isn’t going down. There is water spraying hard out of the weep hole within the pump tank, so obviously the pump seems to be functioning. Cutting the pipe in the pump tank, we can see the pump is definitely pumping hard, but again, the level in the pump tank is not going down. 

We luck out in Wisconsin: our design component manuals require flushout valves at the end of every pressurized lateral. So we can open a flushout valve(s) on the mound to see if water is getting there. In this example, when we open the flushout valve, water sprays out and the level in the pump tank begins to drop. Mystery solved (yes, this early in the article) — the orifices within the mound are plugged with waterborne solids. Even mounds with effluent filters have their orifices plugged. So our answer here is: the laterals and piping within the mound need to be replaced.  

Some try to jet out the laterals, and in some cases it helps. Jetting might open a few orifices and buy some time; however, eventually the orifices will be plugged again. Anybody who has replaced these pipes knows that in some cases what is blocking the orifices is plugged so hard in the orifice that it’s hard to dislodge it even with a pliers, while other orifices merely have the tip of a root coming up through. The majority I’ve seen, no jetting would help. But does this require a total recore, or merely pipe replacement?

In Wisconsin, a total recore of a mound is when you have surface discharge and the mound must be repaired by removing the top layers of the mound, down through the clogging mat, and then rebuilding the mound. Here in Wisconsin, this could include resizing the mound if it was installed prior to our code change in 2000. One symptom that indicates a recore is needed is surfacing of effluent from the mound — the telltale surface discharge. 

But as a Wisconsin state regulator said at a recent conference, just replacing the pipe is not considered a recore if we aren’t changing anything or digging into the aggregate beneath the pipe. 

Of course even when one is merely replacing the pipe, the soil should be checked to determine the existence of and maturity of clogging mat while you have the mound exposed. This is the perfect time to then make it a recore if needed. 

But now let’s answer the pump question in a slightly different way. 

Imagine a similar scenario: A high water alarm has activated, and we are called to a house where the pump is definitely trying to pump — hard. The water is spraying forcefully out of the weep hole, and the level in the tank is not dropping. This one is pumping up to a distribution box and the pump is only four years old. This system has a force main 50 feet long, with 13 feet of vertical lift. 

So now we are up against several possible options. The pump is bad; possibly the float switch; the force main is plugged, frozen or compromised in some way; or the distribution box is bad.   

Unlike the mound, our distribution box is buried so no easy task to test from upslope without digging up the D-box. 

A sewer camera made it through the force main from the pump tank, up through a clear force main, into a distribution box that was just fine. 

So, it’s a bad, four-year-old pump. Don’t let the powerful spray through a weep hole fool you. A bad pump can appear as though nothing is wrong and pump very hard, but in this case not hard enough. 

After checking the pump curve of the pump, it was the right one. Replacing it with the exact same pump pumped the level right down.

I spent a Saturday with a co-worker replacing a pump for a family that just had the pump replaced the day before. A plumber, on Friday, assured them it was exactly the same pump, same brand, same horsepower. Please note, the same brand and horsepower mean nothing. Impellers make a huge difference. This system had 21 feet of vertical lift. If that plumber looked at the curve of the pump they put in, they would have easily seen that the pump they put in never reaches 21 feet of lift. It wasn’t even getting to the top of the hill the distribution cell was in. We replaced it with the exact same pump, with a curve that easily pumped over 21 feet of lift. The power of the pump curve will save you and your customer every time. 

The small effort that made the difference: we called the county for the system records (and saw there was 21 feet of lift), and looked at the pump curve of the pump that was installed on Friday. It was obvious the pump that was just installed could not pump up to the system. A huge mistake by the plumber, but such small effort on our part made all the difference. 



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