Reactivating a sprinkler system in Denver requires balancing landscape hydration with protecting underground plumbing from freezing temperatures. Turning on the irrigation system too early risks expensive damage, while delaying too long stresses turf and plants during dry spring periods. Adhering to local water conservation rules and understanding the mechanical process are necessary steps for seasonal system activation.
Determining the Safe Seasonal Start Date
The crucial factor in activating a Denver sprinkler system is waiting until the risk of a hard freeze has passed, defined by the area’s average last freeze date. Historically, the average date for the last 32°F or lower temperature in Denver is around May 5th, which serves as a reliable guideline for when it is safe to pressurize the system.
Premature activation can be costly because water remaining in above-ground components, like the backflow preventer, can freeze and expand, leading to burst pipes or fittings. While temperatures dropping to 30°F or 31°F can cause damage, the risk is significantly higher below 25°F. Since Denver weather is known for unpredictable spring snowstorms and cold snaps, patience past the average date is a prudent measure to avoid repairs.
Homeowners may need to water during the “shoulder season,” the period between the end of winter and the safe startup date. During this time, it is recommended to hand-water trees, shrubs, and dry patches of lawn using a garden hose. Hand-watering allows targeted hydration without subjecting the entire irrigation system to potential freeze damage. Waiting until the soil has completely thawed, which may require digging a foot or so into the ground to check, further reduces the risk of underground pipe damage.
Mandatory Watering Rules and Time Restrictions
Once the system is activated, all Denver Water customers must adhere to mandatory, year-round watering rules designed to promote water conservation. The most visible restriction is the prohibition of lawn watering between 10 a.m. and 6 p.m. This time-of-day restriction is in place because high daytime temperatures and wind cause significant water loss through evaporation.
The rules also limit the frequency of lawn watering to no more than three days per week. Although three days is the maximum, Denver Water suggests that two days per week is generally sufficient for healthy turfgrass during most of the summer season. Watering plants and shrubs outside of the lawn area is allowed as needed, but still must be done outside the 10 a.m. to 6 p.m. window.
Furthermore, water waste is strictly prohibited, meaning water should never be allowed to pool in gutters, streets, or alleys. Sprinklers must be properly adjusted to avoid spraying water onto concrete or asphalt surfaces. Customers are also required to repair any leaks in their sprinkler system within ten days of detection. Failure to comply with these mandatory rules can result in enforcement action, including fines that begin after an initial warning.
Mechanical Steps for System Activation
The mechanical process of turning on the irrigation system must be executed carefully to prevent a sudden surge of pressure, known as water hammer, which can damage pipes and fittings. Before introducing water, the system controller should be turned off to prevent zones from activating prematurely. A visual inspection for obvious winter damage, such as cracks in exposed pipes or the backflow preventer, should also be completed.
The first step is to slowly open the main water valve that feeds the sprinkler system. The valve should be turned gradually, allowing water to flow in slowly and fill the mainlines over a period of several minutes. Rushing this process can create a pressure shockwave that compromises the integrity of the system components.
After the main valve is fully opened, the backflow preventer valves can be opened sequentially, following the manufacturer’s directions, ensuring the system is fully pressurized. The backflow preventer’s test cocks, which are small slotted screw heads, should be closed by turning the slot perpendicular to the nipple. Finally, test each irrigation zone individually using the controller to check for proper coverage, leaks, and necessary adjustments to the sprinkler heads.