How and When to Drain a Pool

swimming pool
Your swimming pool needs fresh water every few years. But there are several things you need to know before you drain it. In&Out Staff Photo

If you find it’s really tough to keep the chlorine stable in your pool, and the water hasn’t been drained in five or six years, the problem could be the water is “stale.”

When water evaporates over a long period, the remaining water can reach a higher concentration of total dissolved solids and more calcium hardness, according to Sean Webster of Advent Pools. The result is hard-to-balance water and that dreaded white ring around the water line.

The problem is common throughout North Phoenix, and seems to happen even more frequently in Anthem, Webster said. There’s really no cure except to refresh your water, he said, either by backwashing (which will dilute some of the mineral counts) or fully emptying and refilling your pool. You can delay the inevitable by diligently balancing your water and avoiding using shock.

Before you drain

Check the thermometer. Webster warns against emptying the pool during summer: Don’t empty a plaster pool if it’s 90 degrees or higher or a pebble tec pool if it’s hotter than 95 degrees―the heat could cause cracking.

While you’re at it, have that white line sandblasted. “It’s actually silicone, and it’s harder than the calcium deposit so it knocks it right off,” Webster said. Sandblasting costs about $3 per linear foot.

The Right Way to Drain a Pool

Draining your chemically treated pool or spa water into the street or the wash is irresponsible and prohibited. In Phoenix, doing so is a class 1 misdemeanor and may result in a fine of up to $2,500. If you have a small amount of water to drain, consider using it to irrigate Bermuda grass or other salt-tolerant plants.

If you have to empty the pool (or have recently irrigated your landscape using pool water), use your home’s sewer clean-out. But you need to know when to drain a pool, as well as how:

  1. Check the forecast. Don’t drain your pool if the temps are expected to be above 90 degrees.
  2. Locate the clean-out. In Anthem, this can usually be identified by a 4-inch round black cap at ground level in the front or side of the house. It may be hidden by landscaping. If there are two, use the one closest to the house.
  3. Remove the cap and insert the drain hose a few inches into the pipe.
  4. Secure the drain hose so it won’t pop out.
  5. Turn on the sump pump.
  6. Quickly check the shower and tub drains in your house to make sure the sewer valve is working correctly and water is not backing up into the house.
  7.  If water is backing up, your clean-out valve may be stuck or there may be a blockage.  Turn off the pump immediately and consult a plumbing professional.

How Long Will it Take?

A 10,000-gallon pool (a modest size) will take about 14 hours to drain at 720 gallons per hour (12 gallons per minute), the maximum rate recommended by the City of Phoenix. Double the pool size (or cut the pump rate in half) and it’ll take twice as long to drain.

SOURCE: City of Phoenix; Advent Pools

Nadine Shaalan
A Detroit native, Shaalan landed in North Phoenix by way of Philadelphia, Chestertown, Cairo, and New York City. In 2005, she founded In&Out Publications, the parent of North Phoenix News. Before that she was a designer with the Philadelphia Inquirer, and previously co-founded a book-publishing company in Egypt.
Nadine Shaalan on Email

Nadine Shaalan

A Detroit native, Shaalan landed in North Phoenix by way of Philadelphia, Chestertown, Cairo, and New York City. In 2005, she founded In&Out Publications, the parent of North Phoenix News. Before that she was a designer with the Philadelphia Inquirer, and previously co-founded a book-publishing company in Egypt.

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