Colorado’s climate presents a unique challenge for homeowners managing irrigation systems, as the transition from winter to spring is marked by drastic temperature swings. Prematurely activating a sprinkler system can lead to costly damage, while delaying too long can stress the landscape. The primary consideration is protecting pressurized components, particularly the above-ground backflow prevention assembly, from freeze damage. Navigating this process requires attention to regional weather patterns, mechanical procedure, and local water conservation rules.
Determining the Safe Date for System Activation
The most important factor determining the safe date for activation is the risk of a hard freeze, where air temperatures drop to 28°F or below. This temperature range is sufficient to burst pipes and internal seals within the backflow device because water expands as it freezes. Most experts on the Front Range, including Denver Water, suggest waiting until after the average last freeze date, which falls around May 5th in the Denver metro area.
However, the timing varies significantly across Colorado’s diverse geography. Residents in higher elevations or the Western Slope may need to wait until mid-to-late May. Long-range forecasts should be monitored closely, and system activation should be postponed if a cold snap below 30°F is predicted. If the system must be turned on earlier, temporary insulation, such as towels or specialized covers, should be applied to the backflow device as a precaution.
If the landscape shows signs of extreme dryness before the safe date, it is better to hand-water or use a garden hose to spot-treat stressed areas. This technique provides necessary moisture without pressurizing the entire system and risking a catastrophic freeze. Waiting until the soil temperature consistently warms up also aids in healthy turf growth, as grass roots become active when soil reaches 50–60°F.
Step-by-Step Guide to System Reactivation
Once the risk of a hard freeze has passed, reintroducing water to the system must be done slowly to prevent water hammer and component failure. The process begins with a visual inspection of all visible components, including sprinkler heads and the backflow preventer, to check for signs of winter damage. Next, locate the main system shut-off valve, often in the basement or a heated utility space, and open it only one-quarter of the way.
Allowing water to flow into the system slowly prevents a sudden surge of pressure, which can damage internal seals and connections. After a few minutes, the valve can be fully opened, and the system can be pressurized up to the backflow prevention assembly. Many Colorado municipalities require the backflow device to be tested annually by a certified technician to ensure it protects the public water supply from contamination.
After the system is fully pressurized, the control box should be used to run each zone manually for a brief period. This allows the user to visually check for leaks, broken spray heads, and areas with poor coverage. Any observed leaks should be repaired promptly, as a single damaged zone can waste thousands of gallons of water per month.
Navigating Water Restrictions and Initial Watering Schedules
With the system successfully reactivated, the next step is to program the controller according to local utility mandates and water-wise principles. Most major water providers in Colorado, such as Denver Water, impose annual restrictions that typically run from May 1st through October 1st. A common rule is the prohibition of watering between 10 a.m. and 6 p.m. to minimize water loss from evaporation during the hottest part of the day.
Initial spring watering should prioritize efficiency and deep root growth over volume. The recommended technique is called “cycle and soak,” which involves setting shorter, multiple watering periods separated by rest intervals. Instead of watering a zone for a continuous 15 minutes, for example, the controller should be set for three 5-minute cycles with an hour in between each to allow the water to penetrate the soil rather than run off.
During the spring, it is best to water the lawn only two days per week, with a third day reserved only for periods of extreme heat or dryness. This infrequent but deep watering encourages the turf’s root system to grow downward, making it more resilient to the summer’s heat. Adhering to these conservation schedules is often mandatory, and non-compliance can result in fines or penalties from the local water authority.