Recycling Backwash water

David M · Postby **David M** » Sun 08 Mar, 2009 22:21

Hey can any one help. I am looking at recycling the backwash water from my sand filter back into the swimming pool to save water. Does anyone know of a system for doing this or have they seen it done before or done it themselves

David

Postby **Larry** » Mon 09 Mar, 2009 02:59

I believe there are some commercial backwash recycling systems available in Australia where the global freshwater shortage has been the worst. The systems vary from simple holding/ sedimentation tanks to multi-filter reverse osmosis systems.

At its most simple, you would need a tank to hold the backwash water and a pipe running from the tank at 10-20cm from the base to enable you to draw the water off. A valve at the very bottom would allow you to empty the sludge that accumulates.

The backwash water is collected in the tank and the solids allowed to settle. Depending on the amount and nature of the dirt, the addition of a flocculant may be necessary. Once the solid wastes have settled, the clear water can be drawn off and reused. :thumbup:

Things to remember if recycling pool water:

the use of stabilized chlorine (dichlor/ trichlor) will result in excessive cyanuric acid (CYA) and related problems;
the use of calcium hypochlorite (cal-hypo) will cause the hardness level to rise (CH);
the TDS (total dissolved solids) will rise and may cause problems at high levels.

One option that allows fresh water replenishment is to sometimes use the recycled water for your garden and fresh water or rain water to top up the pool. Make sure to let the backwash water sit for several days in hot weather to allow all the chlorine to dissipate. Never try this with a saltwater pool!

David M · Postby **David M** » Mon 09 Mar, 2009 16:32

Thanks Larry. Do you know of or does anyone else know of actual examples where recycling of backwash water back into the pool is being done?
David M

Postby **Larry** » Mon 09 Mar, 2009 16:46

Hi David

Try a Google search, something like: swimming pool backwash recycle and go through the results.

The majority of the results are Australian and there aren't may graphically explicit drawings or pictures. I assume the systems are so simple that if they gave too many details, the makers would lose too many sales to DIYers.

Larry

pool97 · Postby **pool97** » Sat 11 Jul, 2009 21:55

There is a pool backwash system that waste only 1 gallon of water per backwash on residential pools and 5 gallons per backwash on commercial pools. On average a residential pool backwash and rinse cycle wastes 175 gallons of perfectly good balanced pool water. If you backwash once a week you are losing 9100 gallons of water a year not to mention the 9100 gallons of make-up water that must be added back into the pool and also balanced. 18,200 gallons compared to 104 gallons with the ENVIR-O-SMART system do the math on the savings of water, chemicals, and the environment. Commercial pools need this system more than residential pools because commercial pools need to be backwashed everyday. During a 1 year period a commercial pool wastes 109,500 gallons then 109,500 gallons of make-up water is added back to the pool and must be treated. 219,000 gallons compared to 3640 gallons per year with the ENVIR-O-SMART. ENVIR-O-SMART products (912) 294-5178

David M · Postby **David M** » Sun 12 Jul, 2009 17:25

Hey Pool 97,

do you have a web site for this Envir-o- smart product? David

delmonteken · Postby **delmonteken** » Mon 20 Jul, 2009 12:28

I honestly dont think there is a way of doing what you are requesting, The reason I say this is I live most of the time in Spain and when backwasking the pool water the gate valve automatically routes the dirty water to the waste and away. I really think there would be an on cost should there be a way of recycling the backwashed water. I do honestly think if there was someone would have come up with the idea before now.

David M · Postby **David M** » Mon 20 Jul, 2009 17:13

I believe Certikin are marketing a system in the UK to recycle back wash water using a secondary filter.

superdoopie · Postby **superdoopie** » Sat 25 Jul, 2009 06:53

In the area where I live one of the counties requires the use of a separation tank to filter out the DE from the backwash water and let the water go back in to the pool. This is the general idea: http://www.tropixpools.com/SearchResults.asp?Cat=9155 (this is just from a google search not a recommendation of the site).

Anyhow you'd backwash and the waste water goes into the tank which has a bag filter in it. The de gets caught in the filter and the clean water goes back into the pool. I think this would work with a sand filter as well. Do a google search for "separation tank pool" and you'll find them for about $300.

Hope this helps.

Postby **czechmate** » Sat 25 Jul, 2009 21:03

I am missing the point of a value of such a system.
Every pool accumulates CYA and calcium hardness.
So every pool benefits from diluting by a backwash once a while.
To me the extra costs, equipment and mess involved, hardly justifies such an application.

superdoopie · Postby **superdoopie** » Sat 01 Aug, 2009 13:15

Don't get it either. The municipalities don't want the pool water going out into the environment I guess. They are a pain to work on by adding another tank to open and clean out and put back together. They stopped requiring them years ago but they still exist.

poolguy1963 · Postby **poolguy1963** » Sun 16 Aug, 2009 08:08

The envir-o-smart system is available. The website is http://www.envir-o-smart.com and is still under construction. It explains the system and has the ordering info. Residential is one gallon per backwash and commercial is 5 gallons per backwash. This system was designed, developed and built by a professional poolbuilder in south GA.

poolguy1963 · Postby **poolguy1963** » Sun 16 Aug, 2009 13:08

David M wrote:Thanks Larry. Do you know of or does anyone else know of actual examples where recycling of backwash water back into the pool is being done?
David M

THERE IS ONE I KNOW OF IT IS IN SOUTH GA. I HAVE SAW IT FIRST HAND. THE PERSON THAT DESIGNED IT HAS ONE ON HIS POOL.IT HAS BEEN IN USE FOR TWO YEARS .HE IS A POOL BUILDER .IT IS CALLED ENVIR-O-SMART. HE SHOWED ME HIS CHEMICAL BILL FOR A SIX MONTH PERIOD.AND YOU WOULDNT BELIVE ME IF I TOLD YOU WHAT IT WAS.IT WAS LESS THAN YOU WOULD SPEND IN ONE MONTH.

Guest · Postby **Guest** » Fri 04 Jun, 2010 11:35

For my residential pool, I use a 55gal plastic drum. I cut the pvc line to the waste pipe and reconnected to the drum. I backwash into the drum. I have a drain about 4 inches above the bottom of the drum with a plastic garden hose connector/valve assembly. After I backwash, I put a little chlorine in there and let it settle for a day. Then I quick connect a garden hose to the tank. The trick is to let it flow for about 5-10sec to be sure it's clean and no sediment comes out. The I put a sock over the end of the hose and secure it with a rubber band and put it in the pool. Then the remaining 54 gal of clean water drains back into the pool for reuse. This is my 2nd year and it works great. I spent about $30 for all the parts. The 55 gal plastic drum was an apple juice barrel for $10. Nice thing is, I can run the pump on low all the time and backwash every other day since the water is not wasted. Now my power bill is lower too. I have an inground pool.

Guest · Postby **Guest** » Fri 04 Jun, 2010 11:39

I forgot to say, after the water drains back into the pool (this takes 45min or so). I disconnect the garden hose and then tilt the plastic barrel back and forth to stir up the sediment in the bottom. I keep tilting while the sediment drains out onto the ground. Occasionally I have to spray some water in the bottom after the sediment builds up, but not very often. Now it's ready for the next backwash.