In Phoenix, pool and spa water and filter backwash must go to the sanitary sewer through your home's sewer cleanout, not the street, alley, gutter, or storm drain. Discharge at about 12 gallons per minute. No cleanout? A permit is required.
Where pool and backwash water must go
Pool, spa, and filter backwash water has to discharge into the sanitary sewer, not the storm system. The two systems are separate. The sanitary sewer carries household wastewater to a treatment plant. The storm system carries rain straight to washes and rivers with no treatment at all. Pool water belongs in the first one.
The City of Phoenix puts this plainly. Its guidance states that pool and spa owners should drain water "into the sanitary sewer system through a cleanout." That means never the street, the alley, a gutter, or a storm drain. Doing that is an illegal discharge, and it pollutes the waterways those drains feed.
This is not only a local preference. The EPA treats anything other than clean stormwater entering the storm drain as an illicit discharge under the Clean Water Act, and chlorinated pool water is a textbook example. The EPA also reports that improper discharges and blockages drive thousands of sanitary sewer overflows each year, which is why cities are strict about what goes where. Phoenix City Code Chapter 28 governs the sewer system and backs up the City's rules on how connections are used. The Arizona Department of Environmental Quality runs the state stormwater program on the same principle: the storm drain is for rain, and dumping pool water into it can trigger enforcement.
Why does the chemistry matter so much? Pool water carries a chlorine level high enough to be toxic to fish and the bugs and plants that washes depend on. It can also be alkaline and salty. None of that breaks down on its own in an open channel. Sent to the sanitary sewer, the same water blends with normal household flow and gets treated before release. That single difference, treated versus untreated, is the whole reason the rule exists.
A quick gut check: if the water would run toward the curb, the gutter, or a grate in the street, stop. That path is for rain only. If it runs to the cleanout and into the sewer line, you are doing it right.
How to find your sewer cleanout
Your sewer cleanout is the access point into the pipe that carries waste from your house to the City main. Sending pool water here lets it reach the treatment plant the way it should.
Look for a threaded cap, usually about 3 to 4 inches across, often black plastic, sitting close to the ground. It is typically near the house, on the side that faces the street, at the point of the home closest to the city sewer connection. Many Phoenix homes have it in a side yard, a planting bed, or near the foundation. Some are flush with the dirt and easy to miss under gravel or mulch.
To open it, turn the cap counterclockwise by hand or with a wrench. Open it slowly. If the line is under any pressure or holds standing water, you want to know before it splashes. Standing water in the cleanout can also mean the line is partly blocked, which is worth clearing before you add thousands of gallons of pool water. Once the cap is off, you have a direct opening into the sewer lateral, and that is where the discharge hose goes.
If your property has more than one cap, the cleanout you want is the one on the main line running to the street, not a small access for a single fixture. When in doubt, the cap closest to where the sewer leaves your property toward the City main is the safe choice. Homes built on a slab, which describes most of the Phoenix valley, almost always have an exterior cleanout near the foundation.
If you cannot find a cleanout, do not improvise by aiming the hose at the street. Keep reading, because the rules change when no accessible cleanout exists.
How fast you can drain, and the right rate
Speed matters as much as destination. A sewer lateral and the City main can only carry so much at once, and a backyard pool holds many thousands of gallons. Push it in too fast and you can overwhelm the line or cause a backup into your own home.
The recommended ceiling for discharge through a cleanout is about 12 gallons per minute, which works out to roughly 720 gallons per hour. That is far slower than a submersible pump can move on full output, so you will likely need to throttle the pump or use a smaller hose. A typical 15,000-gallon pool drained at that rate takes the better part of a day, and that is by design. Slow and steady protects the pipe.
A few practical points keep the job clean:
- Aim the hose into the cleanout opening, not just near it, so nothing escapes toward the storm drain.
- Watch for backflow. If water starts rising in the cleanout instead of going down, stop and reduce the rate.
- Backwash in short cycles. Sand and DE filters only need a few minutes of backwash; you do not have to send the whole pool through.
- Time it for dry weather. Adding pool water to the sewer during a heavy monsoon storm, when the system is already loaded, raises overflow risk.
What to do if you have no cleanout, plus salt and reuse rules
Not every property has an accessible cleanout, and the rules account for that. When there is no accessible cleanout, discharging to the right-of-way (the street or gutter system) is allowed only with a permit from the City, and only at a much lower rate, under 50 gallons per minute. This is the exception, not the default, and it exists so a permitted, monitored discharge can be managed safely. Without that permit, putting pool water in the right-of-way stays illegal.
Saltwater pool water is restricted. Salt does not get removed at the treatment plant the way other contaminants do, and high salt levels are a known problem for both sewer treatment and any reuse of the water. Because the exact handling rule for saltwater pools can change, treat saltwater discharge as restricted and confirm the current City requirement before you drain a salt pool.
Reusing the water on landscaping is allowed in some cases, but only after the chlorine is gone. Stop adding chemicals and let the pool sit until the chlorine has dropped to near zero (a test strip should read close to nothing), then the dechlorinated water can go onto plants and lawn where permitted. Salt water is generally a poor fit for irrigation because salt builds up in soil and harms plants. Where landscape reuse is allowed, spread the water so it soaks in rather than running off your property.
Step by step, a standard drain or backwash looks like this:
- 1Locate the cleanout and remove the cap slowly.
- 2Run a hose from your pump or filter backwash port to the cleanout opening.
- 3Set the rate to about 12 gpm and start the pump.
- 4Monitor the cleanout for backflow and the yard for any escaping water.
- 5Stop, replace the cap, and snug it down when finished.
Because pool draining sits at the intersection of City code and water quality, verify the current City of Phoenix rules before you start, especially for saltwater pools and for any right-of-way discharge that needs a permit. The City updates this guidance, and a quick check protects you from a fine and a polluted wash. If you cannot find or open your cleanout, a licensed plumber can locate it and set up the discharge correctly. For background, see our pages on what is a sewer cleanout and Phoenix water restrictions.