August 23, 2026 · Updated September 13, 2026

How to winterize drip irrigation before a hard freeze

Water expands about 9% when it freezes, so any drop left in a drip line can split a fitting or crack the tubing. Winterizing a drip system empties every line before your yard freezes hard and stores the parts that crack. The tubing runs at low pressure and drains by gravity, so most of the work is opening the right ends in the right order.

Time the drain to your first hard freeze

A published frost date is an average for a wide area, and your yard rarely matches it. Dense cold air sinks on still nights and slides downhill, pooling in low ground. That pooled air drops your beds and pipes below the forecast low. Our region's calendar puts the first fall frost at 10-22. In our own garden the station logs roughly 7°F under the forecast on most nights, which pulls the first hard freeze in our beds forward to about 09-30. Last year the first frost hit our garden on 2025-10-03.

Drain before the first night that drops well below 32°F. A first light touch of frost does not call for it. A single 31°F night will not freeze a full drip line solid. A run of hours in the low 20s will. The microclimate checker estimates when your own yard freezes by comparing the forecast low against readings nearby home stations logged on recent nights.

Step 1. Shut off the supply and open the ends

Close the valve that feeds the drip zone, then open the flush cap or end cap at the far end of every run. Gravity carries the water out the low end, so open the downhill ends first. Leave them open while you work through the rest.

Step 2. Drain the manifold, filter, and backflow preventer

The manifold, pressure regulator, filter, and backflow preventer hold water in tight chambers that a garden hose bib does not. Open their drain plugs or unscrew the filter bowl and let them empty. The backflow preventer cracks first in a freeze, because its internal check valves trap water against a fixed seat.

Step 3. Clear the low points and any sag

Walk the line and lift each sag so the trapped water runs to an open end. Open or pull emitters at the lowest points, since a plugged emitter holds a small pocket of water that expands against the barb. If you have long runs with sags you cannot lift, a compressor at low pressure pushes the last of the water out.

Step 4. Cap what stays and store what comes in

Once a line runs dry, leave the ends open or cap them loosely so no water collects over winter. Bring the timer, filter cartridge, pressure regulator, and any battery valve indoors, because their seals and electronics fail in hard cold. Coil removable tubing loosely and store it out of the sun.

What can go wrong

• Blowing out at high pressure. Drip emitters and thin tubing split above roughly 25 psi. Keep a compressor throttled low and work one zone at a time.
• Forgetting the backflow preventer. It is the most freeze-prone part and the most expensive to replace. Drain it even if the rest of the line looks empty.
• Draining too late. A hard freeze can arrive days before the calendar says, especially in a low yard. Match the drain to your yard's real low. Ignore the regional date.
• Leaving the timer outside. A battery timer's seals and screen crack in the cold, and a stuck valve floods the manifold on the first spring run.

If you run more than drip, the same freeze logic covers pop-up zones in our guide on when to winterize a sprinkler system. To learn how much colder your own yard runs so you can set that drain date every year, connect a station and let Siltwell learn the offset over about 14 overlapping days on the station setup page. In spring, our guide on drip run frequency by soil covers bringing the same lines back online.