Water pipe from well to house.

[twoskinsoneman]

I have had a decrease in water pressure over several months. I suspect the pump and plan on pulling it, however I also am considering the possibility of a restriction of flow in the water pipe from the well to the house. It's black HDPE and about 150' or so and it also runs under my paved drive way. I really don't want to think about trying to replace it. So here's my question. It there a way to clean it? If it is restricted by some kind of build up can I snake it or something?

Details. I have a submerged pump somewhere in the range of 250-350ft down (I think). It's black HDPE from the pump to the pitless adapter, then the same from the adapter to the house. Then the standard pressure tank and switch. When I turn on a faucet the flow is okay as the pressure tank empties. The pressure switch closes properly and the pump runs but the pressure continues to drop until it levels out at about 10 psi. This is with just one faucet open. So either the pump is damaged so it's not pumping what it should or there is blockage. After I close the faucet the pressure will eventually rise to open the pressure switch but it takes several minutes. I haven't timed it but it's around 10 minutes or more.

 

[Valveman]

Certainly something wrong, but I doubt it is a restriction in HDPE pipe. Most likely the screen on the pump is clogged. It could also be a clogged well screen, but I think you would be seeing air in the faucets. If the screen on the pump is clogged, just remove it.

 

[fixitron]

You have demonstrated that the pump is capable of pumping water to a high enough pressure to satisfy the pressure switch. The fact that it cannot maintain the pressure does indicate a problem, but that could be a problem with the pump as well.
Black water pipe can be crushed. A large rock near the pipe, expansive soils and frost action can crush a pipe that is not deep enough (a proper installation would bury the pipe below the frost line and backfill with clean sand/gravel, and when laid below a driveway, covered with a layer of XPS rigid insulation). IF it were a crushed pipe, the flowrate would be restricted but not the shutoff pressure. A properly sized pump and tank should fill the tank in about a minute or two (typ. somewhere around 10 gal. @ 5-10 GPM). Therefore, if it takes 10 minutes to refill the tank, that would be at about 1 GPM. If your faucet flows at about 1.5 GPM, it could be drawing the water off faster than the pump can supply it, so the pressure drops.
If it were a clogged inlet strainer on the pump, which is unlikely, you would be seeing sediment in the water to your house.
If it is the pump, the motor could be weak enough that it cannot pump the water fast enough. Measure the resistance across the leads and the current draw. If those are higher than the specs for your pump, you need a new pump. You should also check the resistance of each pump wire to ground. If resistance is low, then that leakage could be robbing the pump of enough power to pump properly.

 

[twoskinsoneman]

For posterity sake: changing the pump fixed the issues. After disassembling the old pump it seems like the reason it couldn't move much water is because all the paths in the impellers and diffuses in the pump were thickly caked with hardened sludge. I'm not completely sure what it is but it is black with a red tinge to it. Anyway the new Goulds is working like a champ and it's awesome to have good H2O again.
For fun here's a mid operation pic to enjoy.

 

[havasu]

Thank you for the follow up. Yes, we do like pictures!

 

[Valveman]

Looks great! The black stuff is probably an iron bacteria. You might look into a pellet chlorinator or a Sulfur Eliminator.

 

[twoskinsoneman]

Thanks. Yeah I am having the water tested but I think you are probably right about the iron. 14 years with that pump and never once thought about the need to do anything to the well. Kinda embarrassing but I never gave it any thought until there was a problem. Just turn on the shower and water magically came out. Heh heh heh. Pulling the 325ft pump was my penance.

 

[Valveman]

"We only realize the worth of water when the well is dry." Most people never think about their water until it stops coming out of the faucets. And normally there is little to no maintenance that can be done to a water system anyway. Making sure the pump does not cycle on and off too much is important, but checking the air charge in the tank occasionally is about the only maintenance you can do. Testing the water may have let you know there was iron, but would still not have told you everything would be clogged up. Iron bacteria is tough as it grows in the pours of the pipe and casing. Chlorine only kills the surface layer. So, it takes repeated treatment of some kind to manage it.

 

[twoskinsoneman]

I hope to know more if the lab ever gets back to me with the results but I can't help but feel if I had been doing something as simple pouring a cup of bleach down the well once a month I may have prevented the clogged pump. Yeah I do want to keep the cycles down. I didn't think a CSV would work for me but I did upgrade my pressure tank before the new pump went it.

 

[Valveman]

Lab results will help, but I don't think even that can predict which ones will clog up and where. Now that you know maybe regular treatments will prolong this from happening again. You went from a 20 gallon pressure tank that holds 5 gallons of water to what looks like a 40 gallon size tank that holds 10 gallons of water. Your water doesn't come from the tank, it comes from the well and pump. The tanks only purpose is to limit the on/off cycling which destroys the pump and other things in a water system.

Not sure a CSV would help with your problem, but it would be easy to add and works fine with larger tanks like that. If you irrigate or use water for long periods of time the CSV would cause a slow and steady draw from the well. This is in contrast to surging the water level up and down like happens with a pressure tank only system that is cycling on and off. People who rehab wells for a living like Cotey Chemical Company tell me the steady draw from a CSV helps with lots of well problems.

 

[twoskinsoneman]

Right. The bigger tank (86 gal) is just to cycle the pump less often. My worry with a CSV is that several years ago I dug up the well pipe to the house close to the well and put a T in it to run water to an outbuilding I use for a workshop. I think if I install a CSV at the house my pressure at the outbuilding will go way way up if I understand how those work.

 

[Valveman]

Yes the CSV would need to go before that tee. Depending on your area and how deep the frost line is, it can be installed in a valve box prior to that first tee. However, you can use a tee prior to the CSV as long as the amount of water being used from that outlet is as much as the pump can produce, so there is no cycling while using water from that line. (like matching irrigation zones to the pumps size) It wouldn't work too well for a workshop as you would need to use all the water or nothing from that tee as the CSV couldn't control it.