Elimating the main drain ?

Leaks in the pool, plumbing, filtration system, skimmer, ...
Finding & repairing swimming pool leaks.
Pool Newbie
Pool Newbie
Posts: 2
Joined: Mon 26 Mar, 2012 09:26
My Pool: 16x32 inground with low hung liner
Location: Central Illinois

Elimating the main drain ?

Postby tjmoneypit1 » Mon 26 Mar, 2012 09:52

Don't quite know where to start, but have had an ongoing issue with my inground pool losing water for quite some time now. The pool was installed in 1975 and we have lived here since 1984. In the time that we have lived here, we have put 3 liners in and have spent thousands of dollars to try and stop the pool from losing water. We have sealed off the light nitch, had the plumbing pressure tested several times( always passed with flying colors! ) ,liner seam retaped ( low hung liner), skimmer hole rebuilt, all to no avail. I am presently dealing with a guy that is wanting to convert that low hung liner to a high hung configuration. He also suggested that we could elimate the main drain all together. He went on to say that none of the pools in the south even have main drains. Although I am not worried about getting water out of the pool for winter ( I have a portable pump that will pump it down ) and it would elimate a potental leak source, I am having a little trouble gettting my head around this concept. Is there anything I am overlooking here? In a way it could make some sense, as up here in the north I believe very few if any above ground pools have main drains in them. Any one in the north ever done this ? All input appreciated. Thanks.


Swimming Pool Superstar
Swimming Pool Superstar
Posts: 401
Joined: Sat 16 May, 2009 09:20
My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Elimating the main drain ?

Postby czechmate » Mon 26 Mar, 2012 11:13

tjmoneypit1 wrote: He also suggested that we could elimate the main drain all together. He went on to say that none of the pools in the south even have main drains.

Send the "guy" home.
99.5 % gunite pools in South have main drains. The few gunite pools that do not have a main drain were either built by diletants or main drain was deleted due to a leak on the return piping. Main drain is essential for proper function of any pool sweep cleaner of sand, dust, small debris, DE remnants, etc.
This "expert" is expensive for free!
The unsuported notion, that main drain is not needed was perpetrated by ignorants and common idiots.
Some even proclaimed their lack of reasoning and poor ability to comprehend basic physics right here on this forum.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Elimating the main drain ?

Postby chem geek » Mon 26 Mar, 2012 20:47

This actually isn't a clear-cut topic and there's a vigorous and detailed technical discussion about circulation without main drains on a pool tech forum, but consumers don't have access to that so I won't link to it. Anyway, the point is that from a circulation point of view one CAN design a pool without a main drain, but it requires having returns in the right places generally pointed downwards for a rolling effect and where the skimmers are above those returns (so the water flow goes out and down, up the opposite wall, and back to the skimmer via the surface, like a long loop).

Since good circulation is possible without a main drain if there is a proper design, the benefit of having a main drain is for things like draining a pool using the main pump (though one can often hook up either a separate pump or a hose to the main pump with "vacuum-to-waste"). As for cleaning, there are other alternatives such as pool sweeps to pick up everything on the bottom.

Now, that said, note that most above-ground round pools don't have main drains and their circulation tends to be awful, but that's often because they only have one return so bottom circulation is quite poor. The discussion about return/skimmer placement with no main drain is mostly about larger pools such as commercial/public pools or larger in-ground residential pools.
the shap

Elimating the main drain ?

Postby the shap » Tue 06 Aug, 2013 05:16

I had a new liner put in 2 years ago in my inground pool. The installer pressure tested my main drain line because I had been losing water. He said there was a leak in the line and he closed up the main drain. Boy do I miss it. Constantly having to vacuum crap out of the bottom of the pool. I've been thinking of attaching a hose to one of the skimmers putting a weight on the other end and letting it sit at the bottom of the deep end . Boy do I miss that bottom drain.
bob 11

Re: Elimating the main drain ?

Postby bob 11 » Wed 13 Jan, 2016 16:22

Any real pool with no main drain is unsafe. If a pool has no floor suction, you usually get chemical hot spots. Acid and chlorine are far heavier than water and go straight to the bottom. There they stay, damaging the pool floor without a main drain. My state for the last 60 years has required main drains in every real pool for this reason. If you have to block off your main drain, at least install a suction operated floor cleaner or use some means to provide floor suction when adding chems. Pools without funtioning main drains can have a 15 degree temp difference between shallow and deep water. Anyone who argues this point is probably a salesman with a poorly made product, or an untrained poolman who, instead of doing a proper repair is telling you to block off the main drain. On the bright side I say let any one who offers to pour concrete into your broken main drain do exactly that, then sue them and make them pay for a repair done legally.
Just 2 cents from a guy who builds pools, and hates b.s.

Re: Elimating the main drain ?

Postby bob11 » Wed 13 Jan, 2016 16:57

And a brief comment to the individual who claims to be a California pool professional a few lines up. So there is vigorous discussion among pool professionals about eliminating main drains. REALLY? I have been a pool builder for 30 years and have never heard a good reason for anyone to build or own a pool with no main drain. Most of the dirt in a properly constructed pool goes down the drain, by itself, before the poolman even arrives. If I were to build a real swimming pool in the very state you claim to be a pool professional in with no main drain it would be red-tagged, not allowed to be filled with water. For good reason. I also teach pool cpo classes and in the many actual discussions I have had in these classes with REAL pool professionals, not one person has ever suggested that building a pool with no main drain was a goal of theirs. He speaks of pools with downward facing returns being o.k. with no main drain.....Illegal! main drains are required by law, period.
If you remove your main drain in california and three other states I have built pools in, you will fail your home inspection when its time to sell your home.
User avatar
Pool Forums Admin
Posts: 371
Joined: Thu 09 Dec, 2004 20:19
My Pool: Inground concrete 72m2
Tiled overflow pool
2 Hp pump mono
Fiberglass sand filter 920mm
Tiled deck

Re: Elimating the main drain ?

Postby Larry » Thu 14 Jan, 2016 05:23

Hi Bob

We build and service pools and have always installed a main drain (or multiple main drains, depending on the pool size and pump capacity). In a couple of pool repairs with broken pipes under the shell and where we were unable to break the floor to effect a repair, we substituted the main drain with two wall suction ports where the wall meets the floor. Almost all our pools are concrete.

We service a handful of pools without main drains and it's a pain in the b#tt. Not only are the pools much harder to keep clean, they are also incredibly time consuming to drain and clean when this becomes necessary.

In my opinion, any company that doesn't put in a main drain will not be interested in the maintenance of that pool. The cost advantages in leaving out the main drain are negligible, both in terms of materials and time.

User avatar
Swimming Pool Pro
Swimming Pool Pro
Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

Re: Elimating the main drain ?

Postby mas985 » Wed 09 Mar, 2016 17:32

APSP did this case study a number of years ago. Pretty convincing.

http://www.poolinspections.com/manuals/ ... drains.pdf
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

Return to “Swimming Pool Leaks”

Who is online at the Pool Help Forum

Users browsing this forum: No registered users and 0 guests