Why does an irrigation mainline stay under pressure?
Short answer: The mainline supplies water to the zone valves and is typically pressurized whenever the irrigation water supply is open. It has to be ready the instant any zone valve opens.
The mainline supplies water to the zone valves and is typically pressurized whenever the irrigation water supply is open. It is the pipe between the water supply — through the backflow preventer — and the zone valves, and it holds full supply pressure all the time so that any zone can start the moment its valve opens.
That is the key difference between the mainline and the lateral lines. Laterals only carry water while their zone is running. The mainline never gets a rest, which is why a mainline leak wastes water around the clock and why mainline fittings and the backflow assembly need to be sound.
It is also why the irrigation system needs its own shutoff valve. Closing that one valve takes pressure off the whole mainline, which is the fastest way to stop a mainline leak and the first step in the meter test that proves whether a leak is on the irrigation side at all.
What we check in New Caney
This is a common call in New Caney, and it is the kind of problem we test in the yard instead of guessing at from the driveway. We run the system, watch how the water is actually moving, and check the parts that cause this — before anything gets replaced. That is the same approach in the full Sprinkler Repair service page.
Related reading: Sprinkler Repair in New Caney · All questions · Contact us
Frequently asked questions
Where is the mainline shutoff?
Usually near the backflow preventer or where the irrigation line tees off the main water line. If you do not know where yours is, we will show you when we are on site — it is the valve you want to know before a leak, not during one.
Do I need a professional to look at it?
If the problem keeps coming back, or you cannot see where the water is going, have the system tested before replacing parts. Testing finds the cause instead of guessing at it. Call or text (281) 504-9998 and we will run the system and tell you what we find.
Do you serve New Caney?
Yes. Orion’s Rain serves New Caney 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
- Why is my sprinkler system leaking when no zones are running?
- Why does a broken lateral line leak only when that zone runs?
- Why can a small irrigation mainline leak waste water 24 hours a day?
Get it looked at
If this sounds like your yard in New Caney, 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.
Sources: Leak Detection Bargersville, How to Find a Leak in Your Sprinkler System.
Orion’s Rain Smartscapes and Exteriors — (281) 504-9998 — LI0029444