Cistern

[bluedog225]

Has anybody put in an underground cistern to catch rainwater? I’m having a septic system put in and while the guy is out there I was thinking of putting in a water storage tank underground.

I’ve got a mild preference for underground storage for aesthetic reasons and it will be more protected from damage and UV. The septic guy is pricing tanks, both plastic and concrete.

Is this a good idea? Plastic or concrete, and if I use concrete, is there something I ought to line it with?

Main use will be non-potable water for miscellaneous non-potable use like gardening, irrigation, and maybe firefighting if we get another wildfire. Though I guess it may turn into drinking water in an emergency.

Thanks in advance.

 

[SBAG]

I am going with around 9-10,000 gallons. It’s going to be $20k for the tanks whether I go with 3 plastic or 2 precast concrete. Thinking I might just go with the plastic so I don’t need to get a crane and ease of handling.

No real other option other than pond water. We have a coal seam that jacks with wells (sulfur) and rural water pipes are a mile away.

 

[murd]

I had looked into it when we were getting ready to build our garage, but didn't go for it. In my research I came across a lady a few hours from us that had installed a couple of tanks as they were getting more droughts and having wells run dry. Here's the article, it's not Texas, but its some info for you. I've installed a couple of above ground small systems for the greenhouse.

https://www.cbc.ca/news/canada/nova-scotia/rainwater-system-working-well-port-lorne-ns-1.3772914

 

[CoogarXR]

I have a cistern at the place I just bought. I haven't used it yet, but I know it's there. Many of the neighbors have them too, due to the shallow water table in that area. I guess the well can run dry in the summer if it's a scorcher.

I guess there are some cistern-maintenance things to do; cleaning, water treatments to keep parasites at bay, etc. I haven't looked into it yet. As I said in another thread, some jacknob left the basement window open while the house was unoccupied over the last brutally cold snap, and most of the pipes split, both pumps cracked (the well pump and the cistern pump), the one pressure tank cracked and the other won't pressurize. So I only replaced one pump so far (for the well) to have water while we work on the place. I have yet to experiment with the cistern.

But I did make a switchboard for my future plumbing, so that I can switch cistern/well feeds to the different fixtures:

What did you do "IN" your garage today?

Awhile back when I was painting my HUOT drill bit organizer with RustOleum hammered paint, I noticed changes in the hammered effect based on paint temperature... I noticed when I painted with a chilled can I got more of the hammered effect... I ran a test today and documented the conditions...

www.garagejournal.com

 

[bluedog225]

Ok, that’s pretty nice. I’d not have thought to individually plumb each fixture.

 

[WisJim]

Friends in Minnesota buried a salvaged stainless steel bulk milk truck 2500 gallon tank for their water storage for their household use.

 

[bluedog225]

I’ve heard of those stainless milk tanks. Seem like a great use.

Not many in these parts.

 

[CoogarXR]

Ok, that’s pretty nice. I’d not have thought to individually plumb each fixture.

Thank you!

It's a small log cabin with just one bathroom. I can envision a scorching summer, where I might want to ration the well water, and say only have it run to the kitchen tap, and have everything else run on cistern. But what If I want to pull the camper up and fill the tank with well water? Just flip the valve and run well water to the outside spigot. Things like the toilet will always run on cistern water, but what if the cistern pump dies? Or it has to be emptied for some reason? I'd want to be able to run it on the well too... So I could think of a reason to want access to either source on any fixture, so this was my solution, lol.

 

[Fav Onefour]

I looked into doing one underground as part of a remodeling project. This would have been a concrete tank and poured as part of the structure. It's obviously not a cheap venture going underground. The tanks also need big access openings. Those things all add to cost.

I knew of a monster one I helped build years ago for a truck shop. The tank was same dimensions as the wash bay above. I called those guys to see how it was going after all these years.
The truck wash tank was used for wash bay and utility sinks. They did have issues with gunk over time. Sediment buildup was more than expected but didn't stir up a lot without rain. Said the tank needed to be flushed and scrubbed periodically. They admitted that part sucked. Part of the problem was the design with no gravity outflow. They had to bring in a pumper to clean sludge while guys were in there scrubbing, scraping, and shoveling.

Mine would have been fed with an extensive gutter system. I knew debris was inevitable. The gutters all feed into a single line that runs across the property. I saw the junk coming out that line. I tried testing with filtering that blocked up pretty quick. I tried a settlement catch basin. During high rainfall events the sediment stirred up and flowed through.
The planned location for my cistern would not allow for a gravity outflow.
I ended up not doing the cistern because I just couldn't come up with an easy clean method.

 

[bluedog225]

That’s a good point. Thanks

I can make a point to source a tank with a fitting that will allow me to drain to daylight. I may not spend the money on the trench yet though.

I’m optimistic that debris will not be a problem since the roof is well above the tree line.

 

[Fav Onefour]

@bluedog225 , Do you have any way to check the current output on your gutters?
You probably will be in a better situation with your tree line.

My gutter screens are basic expanded aluminum with a tight fit. I have oaks that are higher than the roof although not close to the structure. I was seeing the pollen from those trees but not getting any large debris.
One roof section that is lower than a dirty set of birch trees. Those are close enough that I figured that water would always be too challenging. I didn't connect that set of gutters to the system. I still saw those seeds in my water from the higher gutters. They must lift and swirl enough to go up on the higher roof.

I can also offer another perspective. We were at an off grid ranch in the jungle above Hilo a few weeks ago. Their above ground tank was about 30,000 gallons and fed from a gutter system. Nearby trees were much higher than the buildings and gutters had screens. The water was used for everything inside and out except for drinking. I asked how much work it was to maintain the tank. Their explanation was pretty casual. Strip down and rinse off before going inside. They scrubbed the inside and flushed everything out the drain. I asked how often and that answer was also casual. "Whenever it needed", was their response. They didn't know if it was once a year or three times. It was simply "Whenever it needed". I'm not really wired to be that casual, but I guess if it works, it's good.
The water seemed pretty decent. They did not have staining on fixtures etc.

 

[bluedog225]

Good idea. I can set something up to filter the runoff and see how it looks. I expect bugs and bird poop. The big crows get up there every morning and eat most of the bugs. Sounds like big chickens running around.

I like the Hawaii approach. I’m not too worried about the quality of the cistern water. I will probably not be drinking it.

Thanks

 

[dcg9381]

Has anybody put in an underground cistern to catch rainwater? I’m having a septic system put in and while the guy is out there I was thinking of putting in a water storage tank underground.

I’ve got a mild preference for underground storage for aesthetic reasons and it will be more protected from damage and UV. The septic guy is pricing tanks, both plastic and concrete.

Is this a good idea? Plastic or concrete, and if I use concrete, is there something I ought to line it with?

Main use will be non-potable water for miscellaneous non-potable use like gardening, irrigation, and maybe firefighting if we get another wildfire. Though I guess it may turn into drinking water in an emergency.

Thanks in advance.

Grandfather had a cistern. Concrete. It lasted a long long time. There may be issues with "water quality" when stored in new concrete, I think it affects PH and what I read is 3-6 months before the PH begins to stabilize to a point where you can drink the water. PH needs to be below 10 for your non-potable purposes.

We are 100% on rain water as our water source. Digging a cistern would be ideal to me, as it's "freeze proof" but it is incredibly expensive to excavate here. Instead I use 5 x 5,000 gallon polyethylene tanks that resist UV. They are interconnected and at different elevations with different roof sources, so one-a-month management to balance is required.




The other common tank type here appears to be steel, they're actually steel panel bolted together and the water is held in a plastic liner inside. These look better, but are also more expensive than the poly tanks that I have:

Good idea. I can set something up to filter the runoff and see how it looks. I expect bugs and bird poop. The big crows get up there every morning and eat most of the bugs. Sounds like big chickens running around.

Use a "first flush" filter. They're on Amazon and other vendors. Basically it mechanically dumps the first X gallons of water off the roof. You do this and a leaf guard and the tanks themselves stay very clean.

I had a lab test our "raw" rain water and it came back very very clean (much better than the well water option). We filter it through a big sediment filter, run it through UV, and then it's drinkable. The house has reverse osmosis system with a series of 3 other filters and more UV for drinking water (just in case).

 

[Hooked]

SIL living in Ohio has lived in a house with cistern only water for 30+ years and as far as I know it's never been cleaned. Water collected entirely by gutter drains into the tank. I checked inside the tank once several years ago attempting to calculate how much water she had remaining. The design of the tank has a cinder block wall dividing in half with the incoming water going in one side and 'filtered' into the other side for household use. If my memory is correct there's a sediment filter in the basement and possibly a charcoal filter.

 

[tez929rr]

I have 5000 gallons in a concrete tank; our fire department has a 5000 gallon concrete tank for well water and 40,000 gallon tank for rainwater. I get the attraction of an underground tank but with a correctly sited above ground tank you can flow water with head pressure. Underground you are going to be pumping. When we have a power outage at the house we can still flow water to all our fixtures. Picture is our rainwater setup. All three buildings (you can’t see the middle one) feed rainwater to the tank and the truck filling site is downhill from there.

 

[tez929rr]

Some other info: some relatively newer concrete tanks in my neighborhood failed after 20 years during a freeze in 2021. We have a 1500 gallon poly tank at our windmill. If I was re-doing the house system I’d use poly tanks. Much less expensive, easy to handle and plumb.

 

[bluedog225]

It’s looking like $1 a gallon is about the best I’m going to find for a water tank.

I’m on a hill. What happens if I get a custom 30 mil pool liner? Or similar tank liner. Less than $1,000 for 10’x10’x10’. Dig a hole, line the bottom and sides with old carpet.

1000 cubic feet is about 7500 gallons.

Put a roof on it and control mosquitoes. Done.

I’d need to pump but that’s not a deal killer.

Seems adequate for irrigation and a fire reservoir.

 

[ericm]

We are 100% on rain water as our water source. Digging a cistern would be ideal to me, as it's "freeze proof" but it is incredibly expensive to excavate here. Instead I use 5 x 5,000 gallon polyethylene tanks that resist UV. They are interconnected and at different elevations with different roof sources, so one-a-month management to balance is required.

What do you do to keep the tanks and plumbing from freezing when it gets cold?

I'm asking because we're planning a new house/shop/garden and it will need a water system. It's in an area that can sometimes freeze, like Austin. The well outfit we talked to is worried about above ground tanks freezing, but we see other properties in the area that have them.

 

[dcg9381]

What do you do to keep the tanks and plumbing from freezing when it gets cold?

Great question. The tanks themselves have so much water in them, in the last 100 year "record freeze" you might get 1-2" of ice around the perimeter of the tank. What you do have to handle is the PVC or PEX "outputs" on the tanks. I use a digital thermostat with a temp probe on the output, set to about 40 degrees, plugged into heat cable and then insulate. I've tried this a few different ways and this works best.



The other way I do it on the main tank is to "circulate" water from the outlet to the inside of the tank. That keeps water flowing 24/7. If you only have one tank, this is probably the way to go.

 

[jubilee]

Lots of railroad tankers buried around here for fire fighting water.
Don't know what they’re going for now.
I bought one in the eighties for scrap price. Think it was 4-5 cents a pound and weighed around 15,000 lbs.
20 -22 thousand gallons. Had some kind of liner in it if I remember correctly

 

[jollygreengiant]

While I get the visual appeal of a buried cistern, what about just installing a pond? Your cost per gallon will be a lot lower and you can have a lot more capacity.

 

[bluedog225]

It’s a fair point. I’m in a nature conservancy habitat program and one of the restrictions is no new ponds. Though I can repair and maintain my existing pond. It’s a ways down hill.

 

[jollygreengiant]

It’s a fair point. I’m in a nature conservancy habitat program and one of the restrictions is no new ponds. Though I can repair and maintain my existing pond. It’s a ways down hill.

That's a head scratcher. You'd think a nature conservancy would encourage more ponds for wildlife habitat?

 

[bluedog225]

Yeah. Apparently they pick ponds and they use ponds. And if you build a new pond, it disperses the breeding pairs more than is good for them. At least that’s what the wildlife biologist said.

 

[dcg9381]

While I get the visual appeal of a buried cistern, what about just installing a pond? Your cost per gallon will be a lot lower and you can have a lot more capacity.

Won't work here. Water loss via evaporation is massive, you'd lose more to the sun that you would daily use. And you're looking at a lot more factors in potentially cleaning up the water. If your land will support a sustainable pond (without a liner), I'd think that you could drill a pretty shallow well at a reasonable price.

 

[Hooked]

Several years ago, a friend put in an underground water storage using 2 - 5' diameter concrete pipes. I think each pipe was 6' long. He rented a mini-ex to dig the hole then had a concrete slab poured to set the pipes on. After doing the plumbing he dropped lids on top then I backfilled over them. I'd have to ask him for confirmation since it's been several years but I think, in addition to garden use, he also plumbed them to his toilets and garage sink.

 

[bluedog225]

Unfortunately, Wild Star coming in at 425’. And lots of demand on the aquifer is drying them up.

edit-“wild star”??? Wtf.

Sb- “Wells are”

 

[SBAG]

Won't work here. Water loss via evaporation is massive, you'd lose more to the sun that you would daily use. And you're looking at a lot more factors in potentially cleaning up the water. If your land will support a sustainable pond (without a liner), I'd think that you could drill a pretty shallow well at a reasonable price.

Wells won’t work where I am (northern MO) and other parts of the Midwest. Large swaths of high sulfur coal. Nor would I try to treat pond water. Most folks have piped rural water. That’s a mile from me and I’d have to pay trenching and materials.

 

[jollygreengiant]

Why would you not want to treat pond water? Apart from more particulate filtration, I don't see why it would be any different than treating other water sources?

 

[bluedog225]

It’s just extra nasty. Lot’s more work.

 

[Hooked]

Bluedog225, what part of Texas?

 

[bluedog225]

Near Smithville

 

[dcg9381]

Why would you not want to treat pond water? Apart from more particulate filtration, I don't see why it would be any different than treating other water sources?

I don't know of anyone who is pulling drinking water from ponds in Texas. Lakes, yes, but those are commercial operations with chlorination and full time staff on water quality. It's likely to have coli-form, biologic growth in it, impact from UV.

To properly treat water you have to know what you're staring with. A pond is going to be a variable environment.

It can be a HUGE difference in complexity, maintenance, required equipment, etc with water that has large set of issues to deal with.

It's not as simple as running things through a series of sediment filters.

 

[niget2002]

Near Smithville

Pretty area down there. I have a lot of family there.

 

[bluedog225]

Thanks. It is nice. Though it’s getting crowded. Musk isn’t helping. I guess it was inevitable.

 

[BombShelter]

I'm pretty sure a cistern is illegal here, check your local codes. I've run across many different types and styles, most are very old but one was maybe from the 70's and it was huge, maybe 10,000 gallons?

Personally I'd do a plastic or fiberglass reinforced tank but they won't be cheap, especially the larger sizes. The problem up here is with a few rainstorms, they fill up pretty fast, I think if you 1/2 your roof size, every inch of water would add a gallon, so a 1000 sq/ft roof would be 500 gallons after an inch of water (the real number is something like (sq/ft)/2.21).

Safety is a huge concern but here they get stinky, yep that swamp smell in you backyard, it's really nice on a hot day and the insects will breed like crazy.

 

[dcg9381]

Personally I'd do a plastic or fiberglass reinforced tank but they won't be cheap, especially the larger sizes.

Roughly $0.60 per gallon around here for 5k gallons. You can't do concrete for that price.

The problem up here is with a few rainstorms, they fill up pretty fast, I think if you 1/2 your roof size, every inch of water would add a gallon, so a 1000 sq/ft roof would be 500 gallons after an inch of water (the real number is something like (sq/ft)/2.21).

A 4" pipe will flow about 240 gallons per minute at gravity pressure.. Assuming your gutters are that large or larger. Rate of rainfall is the big deal. I collect about 3,000 gallons per inch of water, assuming that the water falls at a reasonable rate. It helps to have big gutters and multiple downspouts.

Safety is a huge concern but here they get stinky, yep that swamp smell in you backyard, it's really nice on a hot day and the insects will breed like crazy.

I've had mine up for years and haven't had that problem. Vents have insect screens, we use first flush, and all inlets have screens. These are no-UV tanks, so maybe that helps... Dunno...