Why does the lowest sprinkler head drain after the system turns off?
Short answer: Because water left in the pipe runs downhill to the lowest point. Water remaining in the lateral pipe can move downhill and escape through the lowest head after the zone stops running.
When a zone shuts off, the lateral pipe between the valve and the heads is still full of water. If the yard slopes, gravity pulls that water down to the lowest head on the zone, and it drains out there — sometimes for several minutes after the zone stops. This is called low-head drainage.
A little drainage after shutdown is normal on a sloped yard, but it wastes water, leaves a soggy spot at the low head, and can wash out the soil around it over time. It is also easy to mistake for a leak, since the head keeps dripping long after the system has stopped.
The fix is a check valve — either a head with a built-in check valve or a separate check valve on the lateral — that holds the water in the pipe after shutdown instead of letting it drain out the low head. Heads with built-in check valves are the usual answer on a residential system.
What we check in Kingwood
We check whether the draining head is the lowest one on the zone and how long it drains after shutdown. If it is low-head drainage, we replace the low heads with check-valve heads so the water stays in the pipe. If a head drains when it is not the low point, we look for a valve that is not closing all the way instead.
Related reading: Sprinkler Repair in Kingwood · All questions · Contact us
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Frequently asked questions
How is this different from a valve leaking?
Low-head drainage stops once the pipe empties — usually within a few minutes. A valve that is not closing keeps feeding water, so the head leaks or runs indefinitely. The timing tells us which one it is.
Does low-head drainage waste much water?
It adds up over every cycle, and it all lands in one spot, which stays soggy and can wash soil away from the head. A check-valve head stops it for good.
Do you serve Kingwood?
Yes. Orion’s Rain serves Kingwood and the Lake Houston area — Kingwood, Atascocita, Porter, Humble, New Caney, Summerwood, Fall Creek, Huffman, and Eagle Springs. Call or text (281) 504-9998, 24 hours a day.
Related questions
- What is a sprinkler check valve?
- Why does water continue leaking from sprinkler heads after the zone turns off?
- Why is my yard muddy when it has not rained?
Get it looked at
If this sounds like your yard in Kingwood, call or text Orion’s Rain at (281) 504-9998 — 24 hours a day. We will test the system and tell you what is actually wrong, and what it will take to fix it the right way.
Orion’s Rain Smartscapes and Exteriors — (281) 504-9998 — LI0029444