Why October matters in Caldwell
The Caldwell Municipal Irrigation District, which runs pressurized irrigation for part of the city, says pumps turn on about April 15 to 30 and off about October 1 to 15. NOAA normals for the nearby Nampa station put the median first fall 32 degrees F date at October 13 and the median last spring date at April 29.
That means a system left full past mid October is at risk. If you read this after the date has passed, do the blowout now, before the next cold night.
The blowout, step by step
Shut off the supply
Close the irrigation valve and leave the water off until spring.
Drain the backflow device
Open the test cocks and drain the assembly, then leave handles at a 45 degree angle.
Connect the compressor
Use a regulated air supply at the pressure your system manufacturer lists.
Blow out each zone
Run one zone at a time until only mist comes out of the heads, then move on.
Do not use too much air pressure
Too much air can burst fittings and heads, and it can hurt the person holding the hose. Use a regulator, stay clear of the heads and wear eye protection.
If you are not sure how much pressure your pipe can take, ask an irrigation or plumbing professional. A pro with a regulated compressor does this in less than an hour.
Want a pro to handle it?
Call and the plumber can drain the system, protect the backflow device and check the lines before winter.
Irrigation rules and backflow testing in Caldwell
Homes on pressurized irrigation cannot use city drinking water for irrigation, and the pressurized system is separate from the drinking water line. The Caldwell Municipal Irrigation District runs the seasonal pumps, so blowing out your lines does not depend on the city water department.
The City of Caldwell requires backflow assemblies to be tested every year at the owner's expense, and keeps a list of approved testers. Contact the water department at 208-455-3070, option 2, or backflow@cityofcaldwell.org, for the list.
Irrigation hookups and backflow assemblies are plumbing work under the 2015 Uniform Plumbing Code (UPC) as Idaho amends it.
Source: Caldwell Municipal Irrigation District and City of Caldwell Water Department backflow pages
Protect the backflow device and the main
A backflow device is the most expensive part of an irrigation setup and the most likely to freeze. After draining it, wrap it in a foam cover and leave it open so any water left can expand without cracking the body.
Look at the house shutoff for the irrigation line and exercise it. If it is stuck or leaking, replace it before winter, because a failed valve at the wrong time can send water into the yard.
Signs of a spring irrigation leak
A zone that runs weak
A cracked pipe or head is leaking water.
A wet patch with the zone off
A stuck valve or a broken line is leaking.
Low pressure across zones
A main line leak before the valves.
A spike in the water bill
Irrigation on city water can run all night.
A geyser at a head
A broken head or riser is spraying.
Water in the valve box
A valve is leaking or a wire is shorted.
Winter-ready checklist
- Irrigation supply valve closed and the line drained
- Backflow assembly drained, test cocks open and wrapped
- Each zone blown out until only mist comes from the heads
- Controller set to rain-off or winter mode
- Valve boxes checked for water and cracks
- Hose bibs drained and covered
If a freeze already broke a line
A split line shows up when the system is turned on in spring. Turn it off again, mark the wet spot and call. Leak detection can find the break, and a plumber can replace the damaged section.
For a leak on the pipe between the meter and the house, see water line repair. Do not wait, because a running leak can erode soil and raise your bill.
Questions Caldwell homeowners ask
The Caldwell Municipal Irrigation District says pumps turn off about October 1 to 15. Check with the district for this year's dates.
Yes. The district shuts off the water, but the water in your pipes can still freeze. Blow out the lines after the pumps shut off.
Maybe, if the pressure is regulated and the volume is enough. Many small units cannot move enough air, and a professional compressor does the job faster.
The City of Caldwell requires an annual test at the owner's expense. Call 208-455-3070, option 2, for the approved tester list.
Water left in pipes, valves and the backflow device can freeze and crack them. You may not know until spring.
Yes. See the page for Middleton and the service area page.