Up until very recently, I've never lived anywhere where I had the space to set up an outdoor garden. I've been fortunate to finally own a property where I can, and I'm really enjoying it. So far I've set up an 8 x 25 garden plot, planted 4 fruit trees, and have a thriving wildflower garden in front of the house. I have a lot to learn, but I'm certainly enjoying the process.
One of my recent projects has been to install gutters on my workshop; it's a 25x50ft building. That got me thinking; why not collect the water from the gutters? I live an area that gets near-constant rain in the fall, winter, and spring, but it turns into a desert here during the summer. We haven't had more than a light mist in about a month or more. I have a roughly 60x20ft section of property hidden behind the shop, and it would be a perfect place to set up some IBC totes to collect the water.
For those of you who collect rain water for your garden, how much do you find you need/use? Based on my water bill, it looks like my usage went up by about 75 gallons per month since I've started gardening. I figure round that to 100G just to be safe; for 4 months with little rainfall, that would mean I need about 400G stored. I tend to over-engineer everything I build, so lets double that to 800G.
I'd enjoy hearing from anyone who harvests rainwater for their garden. How much water storage do you have? Do you find it's too much, not enough, or exactly what you need?
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 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.
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.
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 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.
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.