Frequently Asked Questions

Here you will find answers to many of the most commonly asked questions about our water service. If you don’t find the answer here, please contact us at 720-977-6600 or

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How often should I water my lawn?

Voluntary guidelines or mandatory watering restrictions will be defined by our current drought status. The good news is, you can have a healthy green lawn watering no more than 3 days per week using the cycle & soak method during most of the irrigation season. Download a recommended 3 day per week watering guide and learn more about programming your irrigation controller.

What is a sprinkler zone?

A sprinkler zone refers to all sprinkler heads controlled by one valve (and all the turf area covered by the water spray from those sprinkler heads). Sometimes during a drought, guidelines or restrictions limiting the amount of time you can water each zone of your landscape is part of the response plan. 

What is the best way to water a vegetable garden?

Vegetable gardens do require regular watering to thrive in our arid climate. Generally speaking you always want to water deeper and less frequently. It’s important to let the soil dry out a little between watering. Generally we do not recommend watering vegetable gardens every night, but rather increasing the run time and doing it less frequently. Gardens may require more frequent watering when seeds are germinating. Once plants are growing you may be able to water less frequently. You want to water long enough that the root zone gets thoroughly wet, but not so much that it’s always soggy as that reduces oxygen to plant roots. Keep in mind that afternoon wilt in many of our crops (especially the cucurbits: cucumbers, gourds, melons, squashes, and pumpkins) is natural and normal and doesn’t mean that the plants need a ton of water provided they recover once the temperatures drop again.

Can I haul water in from another location to water
my lawn?

No. The City prohibits the use of water supplied from sources other than the city of Thornton.

Can I capture rainwater at home to save for personal use
like gardens?

Most homeowners in Colorado are now allowed to use rain barrels to collect rainwater. A maximum of two rain barrels with a combined storage of 110 gallons or less are allowed at each household. Collected rainwater may be used to irrigate outdoor lawns, plants or gardens.
For more information on this topic: CSU Rainwater Collection in Colorado.

How much and how often should I water my trees?

Current Drought Status will provide specific directions for how often residential trees should be watered. In general, water trees once or twice a month in the winter, three or four times a month in the summer, using a soaker hose or deep root probe. For each inch of the tree’s diameter, apply 10 gallons of water. A three-inch diameter tree will need 30 gallons of water applied at least once a month. Water slowly so that it will reach a depth of 12 inches into the soil. Most of a tree’s absorbing roots are located in the top 12 inches of soil. If you use a deep root probe, insert it no more than eight inches into the soil. Apply the water at many locations around the tree’s dripline, but not too close to the trunk. Deep root probes can be purchased at home improvement stores. Check out the Thornton Forestry page for more information on trees in Thornton.

If you have specific questions related to how much water a particular plant needs, please call a local nursery or the Adams County Cooperative Extension office at 303-637-8100. Colorado State University’s Cooperative Extension has a website that gives useful information on plant care. Follow this link to ask a Colorado Master Gardner.

Is Xeriscaping allowed?

Xeriscaping is allowed and encouraged in the City of Thornton. There is no minimum amount of lawn required for existing residential properties, however regular maintenance is required regardless of the landscape design. All areas of your lot that are not covered by buildings, sidewalks, decks, patios or driveways must be landscaped or mulched. Weeds and bare ground are not considered landscaping. Landscaping includes living plant materials such as trees, shrubs, grass, groundcovers, flowers, etc. and other features such as fountains, pools and benches. Mulch includes rock, stone, bark and other organic or inorganic materials typically used to retain soil moisture and hinder weed growth. Artificial turf is allowed in limited applications. Artificial turf requires a permit and is allowed in side yards that are not visible from the public right of way and back yards. Click here for more information on artificial turf. The use of artificial trees, shrubs, vines or other plants is prohibited.

Water-wise Landscaping City Code

  1. Water-wise landscaping is required on all development, private or public, in recognition of our semi-arid climate and limited amount of water available for outdoor uses. This approach to landscaping shall be done by incorporating water-wise landscape principles into development permit landscape requirements.
  2. Water-wise landscape principles include:
    1. Promoting the use of low water-demand turf and plants and a balance of landscape materials.
    2. Promoting practical turf areas by limiting the use of high water-demand turf and plants to areas of high visibility or functional needs.
    3. Grouping plants with similar water and environmental requirements together on the same irrigation zone.
    4. Use of efficient irrigation systems.
    5. Use of soil amendments and mulches, generally organic and biodegradable.
  3. No person, organization, or association may create or impose restrictive covenants, conditions, restrictions, deed clauses or other agreements between the parties that prevent the use of water-wise landscaping.

For the full City Code click on this link.
If you have questions about City Landscape Code, please call 303-538-7295.
Check out additional water-wise landscape information on the tips and resources page.

Can HOAs prohibit water-wise landscaping?

Colorado HB 19-1050 states that HOAs shall not prohibit the use of xeriscape or drought-tolerant vegetative landscapes. HOAs can, however, adopt and enforce design and aesthetic guidelines or rules that regulate the type, number and placement of drought tolerant plantings and hardscapes. HB 19-1050 can be found here –

Is artificial turf allowed?

Artificial turf is allowed in limited applications. Artificial turf requires a permit and is allowed for side yards that are not visible to a public right-of-way and back yards. Click here and here for more city code details on artificial turf. The use of artificial trees, shrubs, vines or other plants is prohibited. If you have questions about City Landscape Code, please call 303-538-7295.

Check out additional water-wise landscape information on the Saving Outdoors page. As of August 2022, artificial turf no longer qualifies for a rebate.

Can I use greywater (water from my washing machine, tubs, or sinks) to water my outdoor vegetation?

No. The use of greywater is regulated by the Tri-County Health Department. Greywater use is a public health issue because it contains harmful bacteria and viruses. Both greywater and black water (water from toilets) are regarded as wastewater. Tri-County Health Department regulations state that for any home serviced by a public sewer system, all wastewater must go down the drain. Since Thornton residents are serviced by a public sewer system, greywater use in Thornton is prohibited. Please visit CSU’s website for more information on using greywater and harvesting rainwater.

Can large outdoor fountains, waterfalls or ornamental ponds be operated?

The current drought status will regulate the use of outdoor water features. If Thornton is in a drought warning, the City asks customers to shut down ornamental fountains and ponds that do not recycle water.

Can I wash my sidewalks, driveway or patio?

We recommend using a broom instead of a hose to clean impervious surfaces such as sidewalks, driveways and patios. Try to minimize non-essential uses of water, when possible.

Can I wash my car in my driveway this summer?

During non-drought conditions, vehicles may be washed on any day at residences with the use of a bucket or a hand-held hose equipped with a positive shutoff nozzle. The City encourages customers to limit car washing to no more than once a week but be certain to check guidelines or restrictions for any changes.

Can I fill my pool this summer?

Check the current drought status but in most stages pools can be filled, refilled or topped off as long as water is not being wasted. Use of a pool cover is encouraged to reduce water loss.

Is it water conscious to use automatic car washes?

Many automatic car washes use recycling water systems for their operations. Depending on the severity of a drought, water restrictions may curtail use of car washes.

Why do I see water shooting out of hydrants?

The City of Thornton is committed to providing a safe and reliable water supply to its customers. It’s standard procedure for water utilities to use a certain amount of water to ensure that the city’s infrastructure is maintained. You may see City of Thornton Utilities crews working in the community, allowing water to run into the street. Periodic flushing of fire hydrants and testing of water meters are important preventative maintenance activities that ensure the integrity of the water system, the accuracy of the meter system and the delivery of the highest quality water to our customers.

What are the irrigation practices in City parks?

The City of Thornton Parks & Forestry Division is responsible for maintenance of over 960 acres of parks and public lands. We use a variety of water delivery methods from overhead spray irrigation to subsurface drip irrigation. The City follows a practice called Cycle & Soak when we apply the water to our landscapes. Our maintenance staff will determine water needed for each area based on the location, slope, soil type, sun exposure and vegetation. The water needed is delivered in 2 or 3 watering cycles for a given time-frame. This practice allows for the soil to take in more water over a given period of time and helps to promote deeper roots.

Given the number of acres we have to water, it is not always possible to complete the watering schedules between 10 p.m. and 7 a.m. We also have to give high-use sport turf areas different watering schedules to keep the sites safe for play while maintaining a viable green lawn.

If you have any questions about our watering practices, or want to report a broken sprinkler system component in a park, please call the Parks Division at 303-255-7833 or fill out a service request on My Thornton.

What is considered water waste?

Wasting water is prohibited by the Water Use Rules. Water waste is defined in the Thornton City Code as the intentional, unintentional, or excessive use of water that is not considered reasonable, prudent or a wise use of water for an authorized purpose, but not limited to, by way of example, the following: Allowing water to be applied in any manner, rate or quantity such that the water is allowed to pool or flow across the ground or into any drainage way, such as gutters, streets, sidewalks, alleys or storm drains is prohibited. Incidental runoff from an irrigation system operated in a reasonable and prudent manner is excepted. Failing to repair, for a period of more than 10 days after notice, leaking or damaged pipe, hose, or irrigation components is prohibited.

How will notification of violations for water waste be handled?

A water customer may be issued a warning first to ensure understanding of the water waste ordinance. If the waste continues, a written notice of violation will be personally served, posted on a structure on the property or mailed by regular mail to the violator or the owner of the property. The residential penalty for the first violation is $100, $250 for the second, and $500 for the third violation. Commercial, Multifamily and Irrigation account penalties are $250 for the first, $500 for the second and $1000 for the third. The penalty will be added to the violator’s utility bill for the property. If the third violation charge is not paid within five days following written notice of violation, the water service will be suspended. At all times, representatives of the City will attempt to talk to the owner of the property to discuss the cause of the violation and to offer information on how to correct the cause of the violation. Our primary goal is to help customers be as efficient as possible with their water usage.

Is there an appeal process for violations?

Yes, an appeal may be started by requesting a conference with an Infrastructure Department Representative. The request must be made within 10 days of receiving notice of a violation. Contact the Water Resources Division at 720-977-6600.

How do I report Water Waste?

When you observe water being wasted, we need to know the exact address, the nature of the problem, and what time it is occurring. There are many ways you can report issues. You can call the Water Resources Division at 720-977-6600 or email to report the problem. You can also fill out a service request on the My Thornton App. If you can provide a photo of the water waste, that will help us locate the issue and respond quickly. In the case the city needs to issue a water waste warning, a representative of the city must witness the water waste.

Want to report issues using our My Thornton iPhone and Android application? The app can be downloaded free. The process is quick and easy. When a resident spots a problem, or needs an issue resolved, they simply open the app, select an issue, take a picture if applicable, and tap submit. If a photo is submitted, the app uses GPS to detect the exact location of the reported problem, and then include the location with the service request. The request will then go directly to the City staff member who is most qualified to address it. You can use this app for water waste or any other issue you would like to report to City staff.

What is the status of the state's Turf Replacement Program (House Bill 22-1151)?

As directed by House Bill 22-1151, the Colorado Water Conservation Board (CWCB) is in the process of developing a statewide Turf Replacement Program. More information on this program will become available in Spring 2023. The state has established a Frequently Asked Question page about this new legislation and pending program that will be administered by local jurisdictions.