Sprinkler Startup Leaks and What They Tell You

The first watering of the season is when last winter's damage shows up. Lines that held a little water froze, fittings that were already tired let go, and a backflow device that sat full of water through a cold snap cracked. Here's how to tell what you're looking at.

First, know your water source

Many Boise yards water from household supply, through the Veolia meter. Many newer subdivisions use pressure irrigation, a separate system fed from the river canals and run by the city or an irrigation district. If you pay a separate irrigation charge, you're probably on pressure irrigation. It matters: only household-supply leaks show on your water bill, though both can flood a yard or a crawl space.

Start the system slowly

Open the main irrigation valve partway, let the lines fill, then open it fully. Rushing it can slam water into fittings and cause the very leaks you're trying to avoid.

Mainline or lateral?

The mainline stays pressurized whenever the system's main valve is open. Laterals are pressurized only when their zone runs.

• Wet spot that stays wet with every zone off but the main open: mainline or valve.
• Wet spot that only appears during one zone: that zone's lateral or a cracked fitting near a head.
• Meter moving with zones off and the system on household water: likely mainline or backflow. The meter check.

The backflow device

The backflow preventer above ground near the house is the most common freeze casualty. Water spraying or dribbling from its body or test cocks after startup usually means a cracked part. Under Veolia's tariff, required backflow devices are the customer's to install and maintain.

Signs of a buried leak

• A patch that's greener, softer or sinking.
• Low pressure on one zone; heads that barely pop up.
• Water bubbling around a valve box.

When to call

If the leak is on a mainline under concrete, close to the house, or on the household supply side, a plumbing company is often the right call. Some also handle irrigation; many sprinkler companies handle heads and zones. Ask on the call. Sprinkler line leaks.

Next fall

Blowouts before the first hard freeze prevent most startup leaks.