Max Distance Catchment Tank to Pump

[Ryan.]

Question. How far could one install their catchment tank from their house without causing pump or water pressure issues?

For example, could you install a 15,000 gallon tank 80-100 ft away from the pump/pressure tank that is in the house? In this scenario I’m talking about using a typical grundfos stainless steel 3/4 or 1HP jet pump. Tank and pump would be on level ground (ie no slope or hill between them).

Also, would this present any problem for the gravity flow of rainwater from gutter to catchment tank (tank would be 12” lower than the gutters)?

Thank you in advance for any thoughts you can share.

[microage97]

Once primed level distance doesn't really matter

[MarkP]

There is pressure loss per foot depending on flow rate and pipe diameter. If there is a lot of pipe after the pump the consequence is lower flow rate and higher energy consumption per gallon pumped. If the long run is before the pump there are the same theoretical losses with the added problem that if the losses are bad enough the pump can begin to cavitate. In addition to using more energy to pump harder, the pump might not pump effectively or might run really rough. Any leaks that let water out slowly will let air in somewhat faster or if the pipe is buried might let dirty ground water in. It would however take a very extreme case to start seeing these effects. Use a large enough suction line before the pump and you avoid these problems or put the pump near the tank and use as small a pressure line as is convenient and pay for the convenience with higher energy costs.

I suppose that keeping the suction line above grade to eliminate any possibility of sucking in dirty water has a safety value that you can't put a dollar value on and I wouldn't be surprised if the codes have something to say on the issue.

[leilanidude]

My tank is over 100 feet away and 15 feet downhill from the lowest point of the house. The 1/2 HP pump and two 30 gallon pressure tanks are uphill from the tank and it maintains pressure just fine. One inch line runs underground from the tank up to the pump with 3/4 inch running through the filters and house.