The Always-On Problem: The Main That Does Not Know It Is Off
Most irrigation systems have two plumbing phases. The controller-managed phase, the one that turns zones on and off on schedule, is what most homeowners think of as the irrigation system. But upstream of every valve sits an always-on main, a pressurized line that runs from your house water connection to the valve manifold, charged 24 hours a day regardless of what the controller is doing.
A leak in the always-on main wastes water at exactly the rate of any other pressurized supply line: continuously, regardless of season, schedule, or how many watering days you have eliminated. When a homeowner reduces from five days per week to two and sees almost no change in their bill, the always-on main is the most common explanation. The scheduled water savings happened; they were simply offset by the unscheduled loss.
Proving the Always-On Main Is the Problem
Shut the irrigation entirely at its dedicated shutoff. Now run the meter test with the house also isolated. If the meter still shows movement with both the irrigation shutoff closed and the house valve closed, the leak sits somewhere between the meter and the irrigation tee-off point, possibly in a shared section. If the meter stops with everything shut, the loss is on your side of the shutoff, and opening the house valve while watching the meter tells you whether the house or the irrigation owns it.
For an always-on main failure, locating the breach follows the buried-line playbook: the route gets traced, acoustic listening works along it, and one marked hole confirms the failure before a shovel enters the ground.
Zone Valve Failure: The Slow and Quiet Waster
A zone valve that will not seal passes water into its zone around the clock. The zone may never appear to run, because the trickle is far below what the heads were designed to spray. Instead, one section of lawn stays slightly greener than its neighbors throughout a drought, the soil in that zone feels perpetually damp, and the valve box itself stays wet between cycles.
Zone valve failures are among the most common irrigation leaks in the San Gabriel Valley, particularly on systems with multiple zones and aging diaphragm valves. A valve manifold inspection, with each zone cycled and observed for inter-cycle weeping, typically catches the offender in twenty minutes. The repair, a rebuilt or replaced diaphragm, is one of the more economical fixes in irrigation service.
The Controller Audit: The Cheapest Fix
Before concluding that a leak exists, an audit of the controller schedule is worth running. It is not uncommon for valley homeowners to find a schedule nobody remembers setting, a moisture sensor that stopped responding years ago, or a seasonal adjustment that was applied in August and never revisited. A schedule running four cycles where two were intended doubles the bill with no pipe failure at all.
Confirm the controller's active programs, walk each zone while it runs, and compare the scheduled runtime in minutes per week to the meter reading in the same period. If the meter says more water moved than the controller called for, there is either a leak or a ghost program. Both deserve the same starting point: a call to (626) 898-6169 with both the meter reading and the controller's current schedule in hand.
Summer bill still high after cutting days? The always-on main is the next suspect. Call (626) 898-6169.
✆ (626) 898-6169Summer Bill and Irrigation Questions
How do I test whether my irrigation is adding to my bill?
The two-step test takes about fifteen minutes. First, shut the irrigation at its dedicated shutoff valve and leave everything else running normally for a day or two. If the bill trajectory drops noticeably, the irrigation system is contributing. Second, with irrigation off, run the house-isolated meter test to check for any indoor losses. Separating the two systems is the whole trick: an irrigation leak and a house leak can coexist and compound, but they need different repairs.
What is a valve that 'weeps' and how do I spot it?
An irrigation valve that weeps has a failed diaphragm seal, which lets a trickle past even when the valve is in its closed position. The symptom is one area of the yard that stays damp between watering cycles, with the adjacent plants outgrowing their neighbors. Digging up the valve box often reveals standing water or muddy soil around the valve body. A rebuilt or replaced valve typically ends the weeping, and the repair is modest.
The valve box has standing water in it. Is that always a leak?
Not necessarily. A valve box in a low spot can collect surface water from rain or neighboring irrigation. The tell is persistence: surface water drains in a day, a weeping valve keeps the box wet indefinitely. Dip in after several dry days. If the box is still wet and the soil around it is saturated, suspect the valve rather than drainage. Call (626) 898-6169 to schedule a manifold inspection.