Drain or Backwash your Pool

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SwimPool_BrochureHopping into your pool is one of the most refreshing things you can do on those hot Arizona summer days! But, keeping the water safe and inviting for family and friends means proper treatment and maintenance, including occasional backwashing or partial draining. Unfortunately, pool water discharges can contain environmentally harmful pollutants such as excess salts, elevated chlorine and other chemicals, and even nuisances such as mosquito larvae.

 Below, you'll find our steps and guidelines for draining your pool properly in the City of Mesa. These guidelines also apply when draining spas and fountains. It is best to consult a pool professional to determine when it is necessary to drain your pool and how often to do so.

You may also be interested in our printable brochure.

(NOTE: It does not contain all of the charts and information provided below).

Scroll below or jump down to your topic of interest:

Only Rain in the Storm Drain

A pool owner may be tempted to discharge pool water into the street and gutter that leads to a storm drain. However, the purpose of the storm drain system is to protect against flooding and water damage by quickly removing rain water from our streets. This water gets no treatment and may ultimately drain into washes, lakes, retention basins, community parks, and can even make its way into the Salt and Gila rivers. This is why the City of Mesa has ordinances and programs to reduce pollutants into our storm drains and why the disposal of swimming pool water to the City's storm drain system is prohibited. 

  • The ordinance does not allow you to drain pool water into streets, catch basins, curbs, gutters, ditches, channels, storm drains, and retention basins that are owned and operated by the City.
  • It is your responsibility as a property owner to ensure your property is in compliance with City ordinances.
  • The storm drain system is completely separate from the sanitary sewer system, which is designed to capture and treat wastewater from sinks, toilets and other sources.

Pool water discharge cannot be drained to city streets or the storm drain system.

Properly Drain or Backwash Your Pool

You have two main options to drain or backwash your pool:


    This is a great option since it allows you to reuse water you already paid for and could reduce your landscape water use. Drain your pool or spa water to your desert landscape, lawn or rocky areas on your property and allow the water to percolate into the ground. Be sure to use caution when applying pool water on certain plants since it contains more salt and chlorine than tap water. See our table of salt-sensitive plants below.

    • Salt or saline pool water contains higher concentrations of salts that can be more damaging to plants and soils.
    • Remember to move the drain hose frequently, since water discharge to one location can create stagnant water areas that can attract mosquitoes. Also be sure that the pool water does not flow onto your neighbor's property.
    • Notification or a permit is not required by the City of Mesa when draining your pool.


    See our table of salt-sensitive plants below!


    You can also drain or backwash your pool into your home's sanitary sewer cleanout.

    • If backwashing into the sewer cleanout, do not allow the passage of soil, sediment, rock, sand, debris or other solid material during the discharge. This could potentially create a sanitary sewer overflow in the street and/or on your property.
    • Never drain pool water into or toward a sanitary sewer manhole installed in the street.
    • Option 2 allows Mesa to treat and reuse the water for landscape irrigation or groundwater recharge.


    Occasionally, an in-ground pool has a drain line connected to the sanitary sewer. If not, then follow these simple steps.

    1. Locate the sanitary sewer cleanout on your property and remove the cap (if there are two, use the one closest to the home - see Diagram 1).
    2. Make sure that the pool water is near neutral (pH 6-8), shut off the power to the filtration system at the circuit breaker and turn off the automatic water fill valve if you have one (these steps will not be necessary if you are only backwashing your pool).
    3. Run the drainage hose from a submersible pump in the pool to the cleanout pipe and insert the hose a few inches into the pipe. Be sure to secure the drain hose so it won't pop out.
    4. Turn on the pump and immediately check to make sure no water is backing up into the house (check shower and tub drains first).  If the water backs up, turn off the pump immediately. You may have a blockage, or have the flow rate set too high. The recommended discharge rate is 12 gallons per minute.
    5. Replace the sanitary sewer cleanout cover when finished.
    6. Discharging into a sewer clean-out
    7. After draining your pool, refill it as soon as possible since direct sunlight can damage the plaster or lining if left exposed too long.Check for proper chemical levels every day for a week after refilling.


Use pool water or backwash in your landscape.

Discharging into a sewer cleanout allows Mesa to treat and reuse your pool water.

New homes have two sanitary sewer cleanouts. Always pick the one closest to the home.


Locating Your Sanitary Sewer Cleanout

Buried_CleanoutThe sanitary sewer cleanout is commonly used by plumbing professionals to clear sewer line backups. Look for a black threaded cap about 3 to 4 inches in diameter with a raised square nut on top. It is typically located outside at ground level next to the house (often outside a bathroom or the kitchen). Look carefully, as it may be hidden by landscaping. Older homes usually have only one opening, while new homes have two cleanout pipes.  Some homes may have the cleanout located on an outside wall. See Diagram 1 below.

  • If your neighborhood has alleys, your cleanout may be in the backyard.
  • If you have trouble locating your sewer cleanout, or have questions on safe flow rates, consult a plumber.
  • Do not install the pool or backwash drain line as a permanent fixture. This may violate City plumbing codes or County health regulations and and could contaminate the water when you refill the pool.
  • Using a cleanout in the wall is risky and the potential for water backing up is increased.

Diagram 1. Typical locations of sewer cleanout near your home.

Additional Options / Alternatives to Draining Your Pool

Pump_Truck2If your pool has been subjected to serious contamination (for example, high concentrations of chemical treatment products) or the water cannot be disposed of under the other options previously discussed, you may need to hire a contractor to pump you pool into a water truck and dispose of it properly offsite. Check the yellow pages or internet for septic disposal companies for this service.

Consult a pool professional for more information, but other alternatives include:

  1. Maintaining proper chemical levels in your pool to reduce the need to drain.
  2. Consulting your pool professional to determine if repairs can be made without draining the pool.
  3. Using water restoration systems that can be brought onsite and eliminate the need to drain the pool (search the internet for "treat calcium without draining pools").

Cleaning Pool and Spa Filters

Filter_CleaningThe same rules outlined above will apply when cleaning pool and spa filters. Always be sure to follow the manufacturer's instructions.

  • Cartridge filters should be rinsed over gravel, a lawn or other vegetated area.
  • Use a separation tank for diatomaceous earth (DE) and cellulose fiber filters to capture the DE or fibers.
  • Old DE filter or fiber materials can be dried, bagged and placed into your trash receptacle.


Frequent Questions About Draining Your Pool


The maximum recommended discharge rate to your sanitary sewer is 12 gallons per minute, but will depend on the size of the drain line, distance to the sewer main, and the condition of the pipe. Use caution, as some submersible pumps will discharge water too fast and may cause water to backup into the yard or the house. A pump that operates at 700 gallons per hour is about the right size. Table 1 below will help you determine the approximate time to drain your pool.

Table 1. Indicates the time it will take to drain your pool depending on pumping rate and amount of water you are removing.



Pool water can be safely used to irrigate salt-tolerant plants. But, since it does contain more salt and chlorine than tap water, you should use caution when using pool water on certain areas of your landscape. Avoid spraying pool water directly onto leaves or watering the same area repeatedly. Injury symptoms to look for include yellowing or browning of leaf edges, or of the entire leaf, and/or extensive leaf drop. For best results, wait 3-7 days after treatments before draining to allow chlorine to dissipate. The pH should be in the range of 7-8. Drain the water slowly to avoid runoff and over-saturation of the soil. See Table 2 for relative salt tolerance levels of common landscape plants:

Plants Sensitive to Salt:
Do Not Use Pool Water

  • Fruit Trees
  • Star Jasmine
  • Roses
  • Algerian Ivy
  • Photinia
  • Hibiscus
  • Vegetables
  • Annual Flowers

Moderately Sensitive to Salt:
Limited Use of Pool Water

  • Glossy Privet
  • Pyracantha
  • Lantana
  • Xylosma
  • Juniper
  • Bottlebrush

Salt Tolerant Plants:
Can Use Pool Water

  • Bermuda Grass
  • Oleander
  • Euonymus
  • Rosemary
  • Bougainvillea
  • Natal Plum
  • Texas Ranger
  • Olive
  • Mesquite
  • Ice Plant


Table 2. Shows the salt sensitivity of common landscape plants. This list is adapted from a publication provided by the University of Arizona Cooperative Extension.

Native to coastal areas, Natal Plum is very salt tolerant and pool water can be applied.

Plants like Bougainvillea are also very salt
tolerant and can be watered with pool backwash. 



Acid_washingSince discharges from pool repairs can include solid waste particles and high concentrations of chemicals, wastewater discharges from these activities are not allowed to go to either the City of Mesa storm sewer system or the City of Mesa sanitary sewer system. 

Generally, these types of services are initiated by the property owner under contract or similar agreement with a pool equipment and repair company. It is the responsibility of the property owner to ensure that all pool repair wastewaters are managed by the repair company in a manner consistent with City ordinances.


Pool_Keep_SplashIn our dry desert climate, the typical swimming pool can evaporate its equivalent water volume in one year - up to 25,000 gallons of water. Along with evaporation, you will also have water lost to 'splash out' and as mentioned above, for the backwash process. However, it is also estimated that up to 30 percent of all pools have a leak, wasting lots of water unnecessarily.

Since half of the pools out there have a fill valve (automatic pool refiller), leaks often go unnoticed, and problems are not only occurring in aging pools but in new ones, too. Leaks may occur due to a variety of reasons, like holes, tears, or cracks allowing the water to leak undetected under the pool decking or the pool itself. But more often leaks are a result of plumbing problems or improper seals around fittings.

Find our Water Saving Tips to Keep the Splash In Your Pool [PDF] to learn how to check for leaks and to see the typical amount of water lost each month naturally due to evaporation, as well as easy tips to save water.


  1. The charge for the water used to fill your pool is based on consumption, just like the water used inside your home. It is billed per thousand gallons based on the current City of Mesa rates.
  2. If you fill the pool between April and November, there will be no impact on your monthly wastewater (sewer) charge since the wastewater charge is calculated each April based on an average of the previous winter's usage.
  3. If you fill the pool between December and March, remember that the monthly wastewater (sewer) charge is based on an average of your three lowest monthly winter water use readings between that four month period. So, filling the pool during these months may impact your monthly wastewater fee for the following year. You can contact the Customer Service Call Center at (480) 644-2221 and request a Wastewater Fee Adjustment Form [PDF]. This form would allow you to account for the higher usage so that it will not be calculated into your winter water average for that following year.
  4. The City of Mesa no longer rents fire hoses or hydrant wrenches for pool filling. This practice was discontinued several years ago.
  5. In order to judge the impact of filling your pool to your next water bill, you can read the water meter before you start filling the pool and read it again when the pool is filled. The difference between these reads can be multiplied by the current water rates to calculate the cost of the water used. This may be helpful in budgeting for the cost of the water used.


If you're unsure about draining your pool, or you'd like assistance, you may want to contact a professionally-licensed pool service company or plumber.

The City of Mesa is a proud member ofSTORM.


STormwater Outreach for Regional Municipalities

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