Freeze-Proofing De Drain Lines

[texasmax]

So my DE filter has "saw marks" in the backwash drain line in the 2-foot section or so before it goes underground to connect to the house sewer exit. I live in Dallas. Is this code? Is it necessary? I run the pool year-round. I can't imagine why it would be necessary, especially as there's an open-air vertical drain from where the drain line pops back above ground before falling vertically downward into the sewer line.

Replacing the filter and tweaking some plumbing so figured now's the time to ask

Thanks!

[PoolGuyNJ]

That's not any code requirement I ever heard of. That being said, since you are hard plumbing the backwash line, using either a checked sight glass or unscrewing it to let air in after a backwash and rinse is a good idea to prevent any water from sticking around.

Scott

[AFiremanFirst]

When you say "saw marks" I naturally assume they go all the way into the interior of the pipe. ie there is a small amount that leaks when you backwash. If this is the case, then you also mention that you live in the Dallas area and run your pool year round (as do most all of my customers, as I operate in the north dallas area).

With that said... The big question becomes elevation? Is your equipment at a higher elevation than the open air spill over into your sewer clean out. If it is, then there is likely no need for the saw marks in the line. HOWEVER... If your equipment is not at a higher elevation, then you could have static, or stagnate water in the line between backwashings, which is not a problem when we are above freezing.

But... and this is a big but... if your equipment is lower than the clean out then that water is likely to freeze. This could be an expensive repair if it also freezes the bottom portion of the backwash line. My point is this... I believe your equipment is lower than the clean out (not at all uncommon). And I also believe someone added the saw marks after making such an expensive repair, or maybe they were just pro-active. Either way. Our freeze line is shallow in our area 3-9 inches I believe, as compared to feet as we move north. The freeze line is the distance below the surface of the earth that water will freeze. Now does that mean that you should dig down below our freeze line and add saw marks... Maybe. I have not had a problem with below grade freezing. I have however had the pain of replumbing above grade plumbling that was stagnate.

code... Code in my "town" is that you can drain your pool on your property so long as all the water drained is absorbed on your property and does not contaminate water that travels to the storm drains. So although your saw marks may not be code, they are not likely a code violation either, as the amount spilled during a back wash would be minimal and absorbed on your property.

If you are wanting to make an improvement to your situation... Then I would suggest a water spiket before the water goes below grade rather than saw marks. then you can open and close the line after the majority of the water drains after a backwash.

I hope we have been helpful and thank you for your posting

[texasmax]

Yes, the cuts are there intentionally and leak whenever I backwash... a pool installer referred to them as "saw marks" so I referred to them as that (and, yes, they just cut in with a saw). As far as elevation goes, it's hard to tell as the celan out is on the complete other side of the house, and yes it could easily be a foot or two below. Will take your suggestion on the plumbing- thank you!!

[Jacob Stinger]

I think your problems are pipe pitches down ceaselessly, at that point water will deplete out of the pipe by gravity, and there will be no water towards the incorrect side of the pipe to solidify.