Collecting and using rainwater for watering gardens

[electron]

Snow is almost gone, so it's time to think about the gardens. This year, I would like to start collecting rainwater, and figure out a way of distributing it efficiently to my garden beds. Is anyone else doing this, and if so, can you share more details please? Of course, I also want to integrate this with my home automation

 

[purple_motion]

I have a very manual system. Three 40 gallon olive barrels collecting water from about 1200 sqft roof. They fill very quickly (<10 minutes) with a rain shower.

Then I just fill watering cans or attach a hose to the bottom and have it water the grass via gravity (the barrels are about 2-3 feet off the ground).

I live in the snow belt and it is annoying to disconnect & re-connect the barrels every year. Also, 120 gallons of water does not go very far & does not cost that much either (if I pay the city for it).

 

[Quixote_1]

If you're going to go down that road, you might want to look at greywater systems as well.
The only way I can think of for automating would be soil moisture sensors and possibly using ultrasonic range finders to detect the level of water in your rain tanks. If you want to get elaborate, maybe you could set up a rain-meter and correlate the results with your collection method to see how effective it is.

 

[apostolakisl]

I looked at water useage quantities for irrigation and collecting rainwater in barrells was just waaaaaaaaaaaaaaaaay too little. By a rediculous amount. I would have needed to put in a holding pond. Large water storage systems are available but quite expensive, especially if you want them hidden from sight (buried).

I saw a reasonable approach on this old house that would work well for a small garden. It is a large "bag" that can hold something like a thousand gallons. They put it under a deck so it was hidden. It has a small electric pump to draw out the water when needed. They gave the price on the show, I forget what it was, but I can tell you it was still pricey. It would be easy enough to automate the pump.

No matter what you do, it will certainly be more expensive than buying city water (if it is available), so you are pretty much doing this to be "green", not save money. I know people who live out in the country and have a 30,000 gallon cystern for their in house water and use a well for irrigation. Rain water is wonderful for home use, very soft.

You have to look at your square feet of gutter drained, covered foundation (not square feet of roof as the pitch exagerates), and your rainfall patterns. Where I live in Texas we tend to get large amounts of rain and then long spells of drought, so we need large storage capacity (at least 3 months worth and better to have 5 or 6).

 

[electron]

You guys think it wouldn't be enough water when using soaker hoses (which is what I do now)? I do have access to municipal water now, but it would be great if I could use rainwater. I currently have 6 8'x4' beds, and might add 4 more beds.

 

[WayneW]

You guys think it wouldn't be enough water when using soaker hoses (which is what I do now)? I do have access to municipal water now, but it would be great if I could use rainwater. I currently have 6 8'x4' beds, and might add 4 more beds.

Hook your hoses up to your muni water, read the meter, run the hoses for an hour (without doing much else using water), and then read the meter again. That should give you a pretty good item of the gallonage required. Then you just need to factor in how many hours you want to run and how often you get rainfall.

 

[Kevin L]

Lou's right about the water needed is way more than expected. In 2010 I used 134,000 gallons, with much of it going to the lawn and landscaping. In SW Florida, where I average over $150 per month for water, it would be way too much effort for too little return. I want to open a faucet and know water's coming out without worrying whether my rain barrels are full.

Kevin

 

[JimS]

The general comments about needing a lot of storage are correct. But that doesn't necessarily mean you can't do anything. Rain barrels are fairly cheap and it sounds like you have a fairly limited area you want to water. For larger a septic tank can be used (if allowed by local rules) for around 1000 gallons - I think that might be the cheapest way to go for a mid-size system. Beyond that I have seen country homes with huge underground cast concrete tanks or ponds. I am considering a pond.

For pressure the simplest is to elevate the barrels a few feet if you only want to drip water. Or you can get a small pump.

It takes very little rain to fill a rain barrel. So you need to think about what will happen when the barrel fills up. I like the rain diverters that allow the overflow to continue down the downspout as those go into underground piping that carries the water away from the house. A lot of the cheap systems just let the barrel overflow somehow but the fact is most of the rainwater is going to be overflow. I am thinking I may make my own out of PVC fittings. It would be mounted in the downspout at the level of the top of the tank. I just discovered a Fiskars unit that looks good:

http://www.amazon.com/Fiskars-5962-Barrel-DiverterPro-Black/dp/B00387FP5M

I have seen other units that have a lip inside and that was what I planned to build myself. Water tends to cling to the sides of the downspouts so the lip catches most of it. When the tank fills to the level of the lip the water flows over the lip and down the downspout. Here is a link that shows the basic concept - I don't have any experience with it so not giving an opinion on this brand pro or con...

http://www.gardeners.com/on/demandware.static/Sites-Gardeners-Site/Sites-CATALOG_Gardeners/default/pwr/product-reviews/Gardening/Watering/Rain-Barrels/p/33__991-Downspout-Diverter.html

 

[pete_c]

My water rates have gone up over 100% in the last few months to make up for ineptness regarding maintenance of the local wells over the years in my area or another means of generating revenues because my local town is broke so I am looking for alternative/additional watering means.

In FL the 50 house subdivision put in a common well and feeds for just water sprinkling; which is working for them today. It involved an initial up front costs from all of the homeowners but they are all now able to water their lawns without worrying about the high cost of water in the area.

Today the local golf course is using the rain water drainage from the homes in the area to fill their multiple ponds. My guess is that they are also using same water to water the landscaping. I would probably utilize the same water if my home was adjacent to one of the ponds.

I've tweaked watering the near acre of lawn using mcsSprinklers. I could fit a tank under the deck to be able to utilize stored rain water. What's involved in that endeavor?

 

[JimS]

Pete,

Basically you just need a tank, a pump, and piping to connect it all. But there are always details to be dealt with...

For a tank you might look at farm supply stores like Rural King. I think those are midwest only though... They have various size plastic tanks up to about 1500 gallons. You need to think about how you will drain the system unless it doesn't freeze hard where you are. You need to think about how much storage you need. Some areas get fairly good amounts of rain during the summer, others don't. The northwest gets much lower rainfall during the summer. There are lots of records on line to study. Remember water is HEAVY so the tank needs good supports.

Sizing the pump is a whole matter to itself. Here is a good site:
http://www.irrigationtutorials.com/

Then you need to connect the pump to the irrigation system. I planned to be able to supply the irrigation system from water utility or rain water. If you already have an RPZ or other type of check valve for the utility side (this is usually required) and a master valve you should be able to tap in after those for the rainwater pump. Put a check valve between the pump and where it taps in. When you want to water check the level of water in the tank. If you have enough start the pump and whatever zone valve you want. If not, turn on the master valve and the zone you want.

You also need a good filter on the tank, especially if you have drip zones.

 

[pete_c]

Thanks Jim.

I have small river rock under the deck. The deck itself is elevated about 2 feet or so. I do get a hard freeze in the winter. I have a meter on the egress of the landscaping water pipe; so I can get an idea of what I am currently using. I also have an RPZ valve. The water pressure was so low that I needed to install a pump. I currently utilize a Davy pump - still working fine after 7 years. I called them in Australia once regarding cleaning, disassembling and reassembling pump - very good customer service - only thing is I don't think they sell their pumps anymore in the US.

We have a "farm and fleet" store nearby. This is where I purchased my air compressor from. Some good deals there.

Here in the MW we had a nice wet summer last year but previous years we've had droughts that lasted a month or so. Its hard to tell what will happen this summer. Typically the spring / fall not an issue.

I would leave the current 10 port manifold alone and maybe put in another manifold.

 

[pipeman]

I helped a civil engineer friend with a feasability study for a commercial client in S Fl.
The simple fact is, for irrigation use, unless you have very, very simple needs, or plenty of room for pond storage, the economy is so far out of range, that there is no way it could even be considered "Green".

One acre needs around 6000 gallons to provide 1/4" of irrigation, thats almost 900 cubic feet, so roughly a 10' cube.

Better, I think, to spend money on drip style or other low "loss" irrigation systems, running off your present source.

Sonny

 

[apostolakisl]

This is what they used on a house on "this old house". It fit nicely under a deck. http://www.rainwaterpillow.com/product/product-cost.aspx

But, as you can see, the price is up there.

The big above ground tanks aren't cheap either. There are metal silo type ones that look good in some landscape schemes as well as wood ones, again pricey. The plastic ones just look like. . . well, not good.

Underground cysterns are probably the best, but again, cost a lot.

In short, this is something you do for the following reasons:
1) You are very very very "green" and can disregard practicality and cost/benefit analysis completely (you would be better off donating the money spent on rain harvesting to some other environmental cause in most cases).
2) You live somewhere where city water isn't available and wells aren't easy to dig. For example, wells where I live cost $20,000 dollars or more becuase of the 800 foot depth. For about that much money you could put in a 20,000 gallon cystern. But, keep in mind, unless you get regular rain, 20,000 gallon cystern will get emptied very quickly if you try watering more than a few hundred square feet of garden/lawn. It isn't just about the inches of rain per year, you have to factor the typical rain in each month and design a holding system to carry you through the lean months.

 

[pete_c]

Thanks guys.

In FL (per an HOA meeting suggestion that I made) a common well was installed and pipes to the common well provided to the 50 houses in the subdivision. Not really a lot of grass but enough is provided from the well where you don't have to utilize the city water (high cost). Think it was around $2k for each house in cost.

 

[etc6849]

If you're using rainwater, don't forget to let the Iodine-131 (radioactive isotope from Fukushima) decay off before you water your garden