In Phoenix it's illegal to empty your pool by pumping the water into the street. The city requires you to dispose of the water through your home's sewer hook-up, specifically the exterior clean-out. I tried that today and the result was that water started to leak out between the house slab and the cinderblock wall. I was fortunate that water didn't leak into the house itself, at least none that I am aware of. What is this a likely indication of?

It is an indication that your drain line is partially clogged or that your pool pump can pump too much volume for the diameter of your drain. I would use a garden house, get a siphon effect strated and allow it to drain over several hours, gravity with no electrcity used

The city requires you to dispose of the water through your home's sewer hook-up, specifically the exterior clean-out.And if you tried it in my area you would be cited and brought to court. There's a reason for restricting anything but solids and gray water to enter a sewer treatment plant. The reason being that they would have to process rainwater, pool discharge the same as sewerage driving the cost up to the home owner.
It's inconceivable to me that any city would force you to pump thousands of gallons of pool water into the system to be processed as sewage.
Bob gave you good advice. Either snake the sewer line or cut down on the volume. Good luck, Tom

Thanks guys - I'm glad to read that you don't immedidiately assume I have a broken drain pipe. I will take your advice and have the line snaked and then slow the rate of water. Speedball1, I agree with you that the law requiring homeowners to use the sewage line to dispose of pool water is bizare, especially when you factor in the number of pools that we have in our community. Check the attached link; http://phoenix.gov/waterservices/customerservices/issues/pool/index.html

I see here a key statement which may be your issue "Caution: Using a clean-out in the wall is risky and the potential for water backing up into the home is great.

"The maximum recommended discharge rate is 12 gallons per minute (720 gal/hr). However, the safe flow rate may be less, depending on the size of the drain line, distance to the sewer main, and the condition of the pipe. Most pool filter pumps will discharge too much water too fast and may cause water to backup into the yard or the house. The safest approach is to rent a submersible pump, connect it to a garden hose and slowly empty the pool. Refer to the "Hours Required to Drain a Pool" chart to learn more. A pump that operates at 700 gallons per hour is about the right size." 700 gallons per hour is a large volume of water and some homes can't handle this. I'd just decrease the volume before bothering to snake the line. If you never have any sewer issue except when draining then the pipe might just be fine.

I read the link you furnished where the city mandates draining the pool into the sewer system. Unbelievable!
I wonder how much extra you're monthly payments are. Thanks for the information. Tom