What size RO/DI?????

[aquanut92368]

Hi All,
I understand the RO/DI units, what I don't understand is how the units are sized. Some are 75GPD, 25GPD and so on. How many gallons of filtered water will these units actually produce in a days time? My systems lose about 5 gallons a day. I am looking at a 75GPD unit, will this satisfy my needs for water? If someone can tell me how they come up with the GPD figure for these I would greatly appreciate it. TIA
Kevin

 

[AnotherGoldenTeapot]

75gpd means that if:

1. you have sufficent input pressure from your main water supply and the pre-filter is not cloged.
2. the tempreature of the input water is not too cold.
3. you leave you filter running for 24 hours

then you get 75 gallons of water.

 

[sillingw]

but because we don't have the pressure, the input water is usually cool and the filters start to clog a little as soon as you start to use them, then expect about 50-75% of the advertised rate, my 75 gpd ro/di from kent, gives me around 40 gpd

 

[bcjm]

To get the same amount of RO water, does the 75GPD unit waste the same amount of water as a 24GPD unit

 

[scwilich]

Also, does a higher GPD mean the unit needs more water pressure? I'm about to buy an RO/DI unit but don't have much water pressure, does that mean I should get a lower GPD unit?

Thanks!

 

[Emperator]

i believe that ro/di units work on a 1/3 or 1/4 ratio.

for every gallon of ro/di water it produces, it wastes 3 or 4 gallons.

 

[Anonymous]

Or 75 Gallons/Day divided by 24 hours/Day = 3 gallons/hour.

 

[AnotherGoldenTeapot]

For low pressure installation you can get RO units with a pump that steps-up the input pressure to the required pressure to operate the membrane efficently.

With low pressure you get far more waste water and less efficent filtering of the clean water you do get.

 

[sillingw]

the 25, 50, 75 gallon per day are all made to work with std household pressure, although some areas have very low pressure, in which case you will need a unit with a pump (this would be unusual) They all "waste" a lot more water than they produce, I collect this in a big 44 gallon rubbermaid trash can and we use it to water the plants and garden (in theory, it's full of the stuff that they want, because that's what I don't want in my tank)