Connecting multiple RO storage tanks

[bach2pilot]

I've collected three 5 gallon RO storage tanks and I'm wondering if I can connect them better. I have the RO water line run to a t-connector - one side runs to the faucet and the other side runs to the tanks (all 3 connected by t's).
I think that this setup isn't quite right...I can only get 5 gallons of RO water out before the water starts coming out very slowly. Is there a way to connect these tanks to get 15 gallons out of them? You can't really use any check valves. Maybe a couple of shut off valves to empty the tanks one at a time...Anybody have anything that works for them? Thanks.

[Drewbaby]

You could have them flow over into each other by using bulkheads and flex tubing. Once the water level in the first container reached the height of the line it would flow into the second and so on until it reaches the last container.

[bhammer]

my thought would be to run pvc from tank 1 to tank 2 and from tank 2 to tank 3. Then, only get (feed) water from from one of the tanks. If you ahve the three pvc tunes at the bottom of the tanks, the water should be and stay equal in all three while you feed.

[bach2pilot]

No. I guess I wasn't quite clear enough. The storage tanks are the ones that come with the RO units. The ones that look like little propane tanks. Sorry.

[steve5000]

hi have you checked to make sure your tanks are primed with air, should be at 12 - 14 psi. i have mine plumbed the same as you and can run until they are all empty.

[bach2pilot]

Can you re-charge them with a bicycle pump thru the fitting on the bottom?

[kgross]

You might want to change the size of your tubing. if you use 3/8 rather than 1/4 you will get a higher flow rate. from the tanks father down the line.

Kim

[steve5000]

hi yes recharge them with bicycle pump or car foot pump

[bach2pilot]

Sweet! Thanks for your help. I'll try increasing the pressure first, then see what happens before I try larger tubing. Thanks again.

[kgross]

One thing about increasing the pressure, you will decrease the amount of water that they will hold, but you will increase the pressure that the last of the water has when it is forced out. But small hose will still cause a lot of restriction and slow down the flow.

[dahenley]

just a thought..... most pressure tanks i have seen are just 3 gal. so you might be getting the right amount.....
(might want to check to see if they are 3 or 5 gal tanks..)
just a thought

[dahenley]

also, whats your water pressure? if its low, then the tanks will only hold as much water as they can push water in. inside the tanks is a pressurized bladder so if your pressure is low, it might not be able to push all 5 gal in the tank.

[fppf]

Tank size and storage capacity are not one in the same.
Depending on the tank, some mfgrs will sell them listing the actual size, but that is not how much water they will hold. Other mfgrs will list the storage capacity but the actual tank size is going to be larger then that.

The vast majority use actual size because storage capacity will greatly depend on the air charge pressure and your incoming water pressure.

You can get a rough idea on how much storage capacity a tank will have by using Boyle's law for the compression of the gas. P1V1 = P2V2, pressure units must be in absolute.

tank size - ((charge pressure/water pressure)*tank size) = tank storage
So a 5 gallon tank charge with 10 PSIG (that is 24.7 PSIA) and an incoming water pressure of 50 PSIG (64.7 PSIA) with have a usable volume of about 3 gallons. The largest controlling variable here is the charge pressure. The lower the charge pressure the more capacity you will get, however the water comes out as a trickle the closer you get to the end with low charge pressures.