Septic sprinkler flooding yard after pump shuts off

[Uncle Ben]

Hello, I wanted to see if I could get some ideas to stop my sprinkler from draining water out of the line and flooding the yard after the water pump has shut off every time. I have an aerobic septic system, which is operating fine overall, but an ongoing issue has been that the 2nd sprinkler head that is furthest from the septic system keeps draining all the water out of the pipe, since it is the furthest downstream and is also downhill, so gravity keeps feeding water to it for at least 20-30 minutes after the pump has already shut off. It is flooding the yard in that area and making it total mush, which is impossible to mow because the grass and soil is completely soaked all the time.

I tried installing a spring one-way check valve in-line, directly below the sprinkler head itself. I thought the valve would stop water from continuing to drain from the head after the pump shut off, since it would not have the pressure of the pump, but apparently the gravity (and perhaps siphoning action) is too strong, and unfortunately it continues to behave the same way. I added an image of the in-line check valve that I used, as well as the type of sprinkler head that I have.
I did also consider trying a different type of head, perhaps one that does not have drain holes (if that exists), but it seems that other types will not put out enough volume.

Just to be clear, the pressure after the pump shuts off is not so strong that the spray head continues to stay up. When the pump shuts off, the spray head goes down like normal, but there are drain holes at the bottom of the sprinker assembly that the water continues to drain out of for a very long time. I think if those drain holes were not there then it would just come out of the top instead, but without raising the spray head.

Thanks for any input and suggestions that you can offer!

 

[loganb]

I believe what you want is for a low head check valve, Rainbird calls it a Seal a Matic (SAM) check valve. Same concept as what you tried inline, just built into the sprinkler body itself.

 

[isr2kba]

When zoning the install, it is important to keep each zone as level as possible and avoid heads on the trunk line. That’s precisely to minimize leak down flooding.

There’s always some trash in the lines and that is probably preventing your check valve from closing. Is it possible to put a zone valve instead or maybe they make some kind of self cleaning check valve?

 

[doctordirt]

Ok, I've worked on septics for 45 years. Need to drill 1/16 or 1/8 inch hole in the pipe, inside pump tank above the water. It will spit a little effluent when pump is energized. When pump shuts off water drains, hole allows air to follow, so you only drain what is left in pipe. We do a lot of mound systems and drill them this way allowing water to drain back in to the tank to prevent freezing in the winter. It would work either way.

 

[RTM]

Is a check valve the right tool? They usually are used to stop reverse flow, aren’t they?

If there is a valve to stop on low flow, would installing it after the last “high level” valve help fighting gravity?

never dealt with this, so just asking uninformed questions.

 

[Uncle Ben]

Is a check valve the right tool? They usually are used to stop reverse flow, aren’t they?

If there is a valve to stop on low flow, would installing it after the last “high level” valve help fighting gravity?

never dealt with this, so just asking uninformed questions.

Perhaps. A valve doing exactly what you described is what I was hoping to achieve.

 

[Uncle Ben]

Ok, I've worked on septics for 45 years. Need to drill 1/16 or 1/8 inch hole in the pipe, inside pump tank above the water. It will spit a little effluent when pump is energized. When pump shuts off water drains, hole allows air to follow, so you only drain what is left in pipe. We do a lot of mound systems and drill them this way allowing water to drain back in to the tank to prevent freezing in the winter. It would work either way.

Interesting. I certainly never would have thought of that. Does it matter how high up above the water level I drill the hole? I suppose I could just reach my hand/drill as far down into the tank as possible, and drill the hole as far down into the tank as I can reach??

 

[Sumboodie]

How does that work in winter?

 

[Uncle Ben]

How does that work in winter?

I think he means that the water sitting in the sprinkler heads and in the water line would be able to drain back into the tank after the pump shuts off, which would prevent the sprinkler heads from freezing over in the winter. In my particular case I'm thinking it would not prevent that, since the heads are downhill, and there is no way for the water to drain back. Due to the way my home sits on my property, the only direction to send the sprinkler heads was straight to the backyard, which is downhill.

 

[isr2kba]

I think he’s describing a siphon breaker. Assuming there’s a siphon effect when the pump shuts off and keeps drawing effluent from the tank even after the pump cuts out.

 

[JimH74]

Has your system always behaved this way, or is this a new occurrence?

 

[micromind]

Ok, I've worked on septics for 45 years. Need to drill 1/16 or 1/8 inch hole in the pipe, inside pump tank above the water. It will spit a little effluent when pump is energized. When pump shuts off water drains, hole allows air to follow, so you only drain what is left in pipe. We do a lot of mound systems and drill them this way allowing water to drain back in to the tank to prevent freezing in the winter. It would work either way.

This^^^^^^

Basically a vacuum breaker. It will prevent the line from siphoning after the pump stops.

 

[Sumboodie]

I think he means that the water sitting in the sprinkler heads and in the water line would be able to drain back into the tank after the pump shuts off, which would prevent the sprinkler heads from freezing over in the winter. In my particular case I'm thinking it would not prevent that, since the heads are downhill, and there is no way for the water to drain back. Due to the way my home sits on my property, the only direction to send the sprinkler heads was straight to the backyard, which is downhill.

I meant your setup where the sprinkalater is downhill.

Seems like it'd need a zone valve and computer to keep it off when it's too cold.

 

[Uncle Ben]

Sumboodie: Right, I was wondering the same thing. If the water line runs on a downward slope from the septic tank all the way to the 2 sprinkler heads, then all the water in the line is going to keep running towards the heads, due to gravity.

The water line is probably at least 200 ft from the tank to the last/2nd head, and I'm not actually sure if the water is siphoning, or if it is just draining out the remaining water in the line, but if it is siphoning, then I could see the "drill a hole" solution at least helping that part of the issue.

 

[jar944]

I'm confused how you have a sprinkler on an aerobic system.

Is this what you have?

 

[Uncle Ben]

No, I don't have that component in my system. Here is a photo of a system that looks just like what I have at home. As far as the sprinkler portion of the system, there is just a pump down in the tank and it sends the effluent directly up and out of the tank via a PVC pipe that goes directly to the sprinkler heads out in the yard, and no other components in between.

 

[Uncle Ben]

Ok, I've worked on septics for 45 years. Need to drill 1/16 or 1/8 inch hole in the pipe, inside pump tank above the water. It will spit a little effluent when pump is energized. When pump shuts off water drains, hole allows air to follow, so you only drain what is left in pipe. We do a lot of mound systems and drill them this way allowing water to drain back in to the tank to prevent freezing in the winter. It would work either way.

Doctordirt, would this method basically just take care of the siphoning issue if there is water continuing to be syphoned from the tank after the pump is already off?

I'm assuming there is still nothing I would be able to do about water that is in the horizontal water line that is running downhill from the tank to the sprinkler heads, right?

 

[yatg]

How about an electric valve at each head and tie them to the pump.

https://www.amazon.com/Motorized-Valve-Standard-U-S-Solid/dp/B06XXGMDZK/?tag=atomicindus08-20

 

[bbrins]

I don't know much, if anything about that type of septic system. What about putting in a soakaway in the lawn in that area? Basically, just dig a hole, line it with drain cloth, and fill it with gravel, and put your sod back on top. Whether that will work will depend on your water table.

 

[Uncle Ben]

How about an electric valve at each head and tie them to the pump.

https://www.amazon.com/Motorized-Valve-Standard-U-S-Solid/dp/B06XXGMDZK/?tag=atomicindus08-20

Thanks yatg. The only thing about this is that the heads are way out in the yard a couple hundred feet away from either the shop or the house, so it is far away from any power source. That type of head may not allow enough GPH output for the amount of water that the tank pumps out every day. The type of heads that I have (3/4" thread, which are typically used for this type of system) seem to allow for a fairly high volume.