In Australia, most rural houses have at least 20K litres which is 5K gallons. I know people with over 100K litres.
In suburbia, I had 10K or 2500gal. Ran a small nursery and would go close to empty through drought.
Trust me, more the merrier.
this post was submitted on 22 Jul 2023
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That is a lot of water. I live in a semi-rural area myself; we have access to municipal water and electric, but not sewer or broadband (just twisted-pair copper).
When you say that most houses stored 20K liters, was that solely for gardening / agriculture, or also for household use? I'm not very experienced when it comes to such things, but that sounds like something you would need for an entire household or for industrial farming.
What's kind of ironic is that I live in one of the rainiest parts of the USA (Pacific Northwest), and for a large portion of the year, the rain is just constant. I have lived in the desert before, and the summers here are just as dry as they were back then.
My initial idea was to pick up 5 330G (1250L) IBC totes and link them in series for a total of 1650G (6246L). Part of the reason I made this post was that I had a feeling that amount of water was just excessive for what really amounts to a 4-month period of use. Sounds like I might be doing myself a favor by erring on the side of caution.
20K is enough when the weather is good. We have multi-year droughts so it won't be enough for the house when it's bad. Cities were down to 140L per day so you can't rely on municipal always.
With my 10K, all gardening and outside water was tank. A nursery with our heat uses a lot, daily watering.
100K is full off grid with enough to be sure you can get through a drought and maintain outside watering. Ive seen plenty of house with these: https://heritagetanks.com.au/product/ct25-110000-litre-rain-water-tank-available-east/
I would err on the side of caution. We don't use IBCs because they aren't UV stabilised. Metal or UV plastic tanks are freely available.
A family of 4 with my larger nursery uses 31K every 3 months, it will get higher when El Nino arrives. I can't convince kids to have short showers and we have an ultra low flow head.
At least where I live, both metal an UV plastic tanks are extremely expensive compared to IBCs. I was hoping that painting the IBCs black or covering them with a tarp would help to mitigate the algae growth from sunlight. Wishful thinking?
No, that's good. A wooden structure might also be worthwhile, something with a roof and another gutter? Like a lean to. IBCs aren't made to be permanent, the wall thickness is a fraction of a plastic water tank and can be punctured easily (the cage is why it can be thin). Can you get 200L blue barrels? Daisy chaining them, even a 2x stack is possible, and they are similar to plastic water tanks. Same HDPE, thick walled, UV stabilised, sun not an issue.
Tanks are an investment here. They're not cheap(ish) but it's part of the house, a necessary expense even bordering on survival in a way.
I have three 50 gallon rain water collection barrels and have never fully used them for irrigating my garden, as much as I'd love to. Gravity pressure alone is not enough to use any sort of automated drip system or anything and we've been left having to use watering cans when using the collected rain water. The barrels do fill up quickly after one or two good rains.
I guess my point is to make sure you have a sufficient pump design in mind to use the collected rain water. Best of luck.
So 150G total, then? It sounds like I may be significantly over-estimating the amount of water I need, although I have been wanting to plant grass in a few areas, so it might come in useful for this. How often do you usually get rain during the dry months?
A pump has always been part of the plan. The irrigation system will be right next to my shop, so I can easily run 240V from the breaker panel to a large pump outside. I bet you could find a pump for fairly cheap that would work for your irrigation system. I've seen 120V pumps on Amazon for $100-$150, and since you already have gravity working in your favor, you wouldn't need to get an expensive pump with a high head pressure.
Yeah 150 gallon total but it's definitely not enough to get me though even a couple weeks of watering if I were to rely on it. I probably use close to 60g to water all my garden once and that gets me 2-3 days before I need to water again. And we get pretty much no rain during the summer months, maybe a sprinkle but not enough to fill the barrels.
I've been looking at how to get pumps setup, the problem is it's 3 independent barrels so I'd need 3 pumps and then power. Also unsure if I want to retrofit a submersible pump or use inline on the existing spout.
I don't know how your barrels are set up, but you should only need one pump. Assuming you have a place to make all 3 barrels level with each other, you can install an output at the base of each barrel and connect all three together. When you collect water in one barrel, it increases the downward pressure of the water in that barrel, and it will equalize across the other two; filling one barrel actually fills all 3. Then just install a tap on connection between the 3 barrels and route it to a pump (I'd recommend a particulate filter first so you don't jam up the pump). When you pump water out, the inverse happens; all 3 barrels will drain equally. Even if your barrels are far apart, as long as you can keep them level with each other, this should still work as long as you're willing to run plumbing between them.
Personally, I'd prefer an inline pump rather than submersible. Not only is maintenance on the pump easier, but you also don't have to worry about running electricity into one of the barrels; I'm sure submersible pumps are safe, but you'd still have to cut an opening in the barrel for your power cables, which is a pain in the ass.
As far as power goes, as long as you can position the pump close to a structure with power, you just need to make sure you use liquid-tight conduit between the outer wall of the structure and the pump. If you want an outdoor switch for the pump, this would need to be an a liquid-tight enclosure. While it's almost certainly not to code, you could probably just install a 1-15P plug on the cable inside the structure and plug it into an outlet and have no issues. FYI: I'm not an electrician, just someone who's done a lot of electrical work.
Edit: I just realized that my comments about electrical are very US-centric; if you're not in the USA, it's probably a good idea to disregard everything I just said.
It's been a while since I made this post, but I've finished my rainwater harvesting / irrigation system, and the advice I received here was definitely helpful. I learned some things, too.
- More water storage was the right call. I had initially thought 800G, but I ultimately went with 1650G. Lately, my flow meter has been showing about 100G per day of water usage. I'm watering a large patch of grass seed, so I expect the usage will go down significantly once the grass germinates and I can stop watering so frequently, but I had no idea I would use so much. I've checked and double-checked the math a dozen times, but it's all correct. New grass uses a lot of water. Just to put it in perspective, my grass area uses 3GPM and gets watered 4x per day for 7 minutes each time (and the grass seed still starts to dry in our 90-degree heat). That's 84 gallons of water per day just for the grass. Kind of makes me wonder if grass is worth it, to be honest.
- I bought the biggest pump I could afford: 2HP with a ~70GPM flow rate. It was way too much; restricting the outflow caused the pump to work way too hard, so I had to build a re-circulation system to pass a large portion of the outflow back into the water tanks.
- Algae growth in the water tanks hasn't been the issue I thought it would be. My tanks are positioned in an area that's blocked by a building to the west and tall trees to the east, so they never get sunlight.
- Filtering is absolutely essential. Even with a 6ft section of pipe that catches the initial runoff, the first rainfall still filled the tanks with dirt from my roof. I have a 150 mesh spindown filter followed by a 20-micron canister filter, and I'm very thankful I decided to go with a 2-stage system instead of just the spindown filter.
- IBC totes are a huge pain in the ass. The outlet on my tanks is not a standard threading, and adapters simply do not exist for the particular type of fitting I have; I had to use a rubber coupling between the tank outlet and my PVC plumbing. The tanks expand and shift as they fill, so the plumbing has to have some built-in flexibility. I lost count of how many rubber couplings I had to use, but it was a lot. Bulkhead fittings will leak, so they have to be placed on the top of the tanks with internal plumbing from the fitting to the tank bottom. Using a large purpose-built water tank would have been the best choice, but it just wasn't an option financially.
All-in-all, though, it was a really fun project to work on. I went with a Rachio 3 sprinkler controller, Orbit valves, and ran buried pipe to all the areas that needed water. Everything just waters itself now, and I know exactly how much water each area is getting. Not only does nature provide the water for free, but I'm also not wasting potable municipal water either (at least not as much; I've still had to fill the tanks from the hose a few times). It was well worth the work and the expense; thank you again to everyone who posted here to help me out.
Depends on what your cost of water is. Setting up rain water reservoirs, plumbing it to your garden, and cleaning/maintenance adds up quick. If you’re only watering a small garden, might just want to stick with the hose.
I’ve got about 800gal capacity, and I use it all. My garden is large, and all the excess gets dumped into the pond.
Your garden will get bigger. If it’s legal (where I’m at in the PNW, it’s not exactly legal to do) I’d harvest as much as you can. You’ll find uses for it.
I also live in the PNW; what kind of legal restrictions do you have on rainwater collection? Here in Oregon, it's legal as long as it's being collected from an artifical surface (like a roof). The only information I could find on limits are less than 5000G without a permit.
I’m in Oregon as well!
I just looked, and you are correct. It seems I was misled, or didn’t fully understand, but when I was building my greenhouse I was told by someone that it was not legal in certain counties. But I can’t find any source to back that claim. So I guess I’m not as rebellious as I thought.
My understanding is that not being allowed to catch rainwater is more of a urban legend. People took not being allowed to divert streams and other bodies of water and over time the telephone game turned it into not being allowed to gather rain off your roof.
I believe you are correct. It seems I must have fallen for it. Well I guess I’m not as big of a rebel as I once thought. TIL
Where I live, apparently its illegal? Not rly sure why.
Theoretically it's to help aquifer recharging, but it feels a bit misguided when directed to homeowner gardens, which are far more environmentally beneficial than the amount of roof runoff they would be temporarily diverting.
I wonder what they would do if they caught you doing it.
I wonder if they'd ever even find out or if they did, if they'd even care.
I only use water catchement for the chickens water....since the other choice is to lug water across the property. Water is heavy. It only works for ~8 months of the year too. It's a 50gal barrel, that is full all fall/winter/spring and dry durring the summer.
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