Compensating for low flow/pressure water supply to outbuilding?

[IHDiesel73L]

I am building a small office/guest cabin on the foundation of an old barn on my property. The barn did have electric and water but it was torn down before I bought the property. I've located the services and the electric is adequate but I'm not so sure about the water. The service is 3/4" galvanized pipe that has some corrosion and buildup on the inside (we are on well water that is slightly acidic) plus the barn is about 200' from the house. I haven't measured GPM or pressure yet but just by watching it run out of the pipe I can tell that I'm not getting the normal volume that I would from a new clear 3/4" pipe nor the same 40 p.s.i. that I'm getting in the house. The guest cabin will have a stall shower, toilet and sink. I'll be using a small tankless propane heater for DHW. Mainly I'm concerned about having adequate volume and pressure for a decent shower.

Harbor Freight makes a decent little shallow well pump and pressure tank combo that should boost the pressure just fine but the 5 gallon tank won't keep up with the flow for a shower:

1 HP Stainless Steel Shallow Well Pump and Tank with Pressure Control Switch - 950 GPH

Amazing deals on this 1Hp Stainless Steel Shallow Well Pump at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I'm thinking about bringing the water supply into the cabin and plumbing it into the bung of a 55 gallon poly drum-the other bung would be plumbed into the pump/pressure tank. I figure this way the pump should never be starved for flow even during a shower. With a 2.5 GPM shower head even a 10 minute shower should only draw it down about half way and of course the supply will be constantly filling it back up. Seems simple but am I missing anything?

 

[Handloader109]

200 feet? Put down a new pvc line that is 1"minimum diameter. Way easier than dealing with old pipe that might fail at any time...

 

[Tractor Seabee]

Amen to Handloader. 200' I would probably be tempted to go 1 1/2". Any thing else is a workaround you will not be happy with in the end. What we call a Rube-Goldberg solution.

Ron

 

[plowhog]

the barn is about 200' from the house. I haven't measured GPM or pressure yet but just by watching it run out of the pipe I can tell that I'm not getting the normal volume that I would from a new clear 3/4" pipe nor the same 40 p.s.i. that I'm getting in the house.

How do you know what flow you would have-- even with brand new 3/4 pvc at 40psi, running 200 feet? There is a lot of friction loss in 3/4 pipe, whether brand new pvc or old galvanized.

40 psi is quite low, 3/4 certainly not ideal, and 200 feet not helpful. And you didn't say how old the galvanized is.

Before considering replacement, if it is a straight run, I'd be tempted to increase the pressure to 50-60psi (at the source) and see what you get on the other end of the pipe. If it's close you could also add a booster pump at the end of the 200' line. Also, there are systems that will treat water problems to arrest the minerals or water issues that are attacking or corroding your pipes.

I have a property with 50+ year old galvanized pipe. Some of it is in amazingly good condition. But our copper pipe at the same location suffered from a water/chemistry issue. I had to add a water conditioner to stop the "blue stains" from the former water chemistry/copper pipe issue.

fyi I had some recent well work done, and the technician increased the "high side" pressure to 65lbs. He said for a 2 story house they usually increase to 65-70psi.

 

[Ken45101]

I agree, a new line would be less expensive and more reliable. We have 45psi at the house and about a 200' run to the barn and get around 10 gpm flow. I used the black (polyethene?) roll of pipe, maybe 1-1/4", i don't remember. The barn contractor thought it was unnecessarily large but he obviously didn't understand pressure and flow losses. I'm glad I didn't let him size the line.

BTW, the rural waterworks told me they consider anything above 40 psi to be acceptable. We have 2000' of 1-1/2" line coming from the road with a 150' elevation gain (75 psi loss for the elevation gain.)

Ken

 

[ultrarunner]

Brother is on gravity spring water which provides 34 psi at the home...

Everything works fine but he up sized piping to compensate...

 

[4570Man]

Your 40 psi input pressure is pretty low to start with. You’re already at a big disadvantage trying to push water 200 feet with that. If you can increase the input pressure you might get satisfactory results without anything else. My second recommendation would be to abandon the galvanized line and run a new 1” at minimum sized line.

 

[ultrarunner]

Is the 200' level, up hill or down hill?

200' up hill introduces added loss.

Had old galvanized at an old house the had been vacant... not able to get good flow...

I set up a pump to circulate CLR over a few days through the system...

It did clean out the pipes of rust, sediment and corrosion...

I think if I had any long range plans bite the bullet and run a new line and be done... while open drop some empty conduit for future needs?

 

[jyoutz]

200 feet? Put down a new pvc line that is 1"minimum diameter. Way easier than dealing with old pipe that might fail at any time...

Absolutely. A cheap and easy fix.

 

[bdhsfz6]

I agree with the others who recommend replacing the water line. I know from experience that this is often easier said than done.

I have a water supply line out to my barn with a similar flow issue. In my case, there is no easy route to run a new line due to concrete patio, asphalt driveway, etc. I used one of these well pressure tanks to fix the problem. No pump is required:

WX-250 - Amtrol WX-250 - WX-250 (145S1), 44 Gal WELL-X-TROL Well Tank (Stand)

The existing low flow line charges the tank to the same pressure as the house and gives me local water storage at around 50 psi. The tank I have is 50 gal which gives me plenty of water for washing machinery. If the pressure runs low, I just wait a couple of minutes for the tank to recharge.

If you have the space for a tank, I think this principle might work for a hot water heater and shower.