In the past it was common practice to catch rainwater, especially on farms where large barn roofs and thirsty animals made a good combination. In the area where I live water is scarce. Drilling a well was a gamble I didnt want to take so I planned on catching water from the start. Another problem was that about 3/4 of the rain falls in a short period of time in mid summer, this makes a larger storage system necessary. What i have now evolved over a period of 4 years. If you are about to set up a system, don't reinvent the wheel, take what I have done as an example of what works.
Rainwater is great for plants, showers and of course flushing the toilet. Evaporative cooler pads will not load up with minerals because there arent any minerals in rainwater. As a bonus, will also use less detergent in the laundry.
My rainwater catcher started out as a single 1550 gallon tank set at the corner of the house. I quickly found out that having just a 1550 gallon tank was like having a single battery in the middle of a wind storm.. I just couldnt catch enough. Watching the tank run over only to make the driveway muddy was very frustrating.
I installed standard raingutter on the house and used a 1 inch drop in 18 feet using the center of the house as a starting point. This makes half the water run off each corner of the house. The big thing You dont want is low spots anywhere in the system. Water is very heavy and will bring the gutters or pipes down easily if not installed correctly.
There are 7 downspouts between the garage and house and all of them go approx 12 inches below the level of the inside floor. I figured this height based on hanging the 4 inch pipe from the decks that were to be built later.
The 4 inch pipes run the full perimeter of the house and they have enough drop so that the water drains out in one spot. I could have easily gotten by with 3 inch pipe but at the time had no idea how much it would handle and where the bottlenecks would be.
The catchtank and roofwasher sits at the corner of the garage. The pressure pump sits temporarily on a cement block.
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A common trash can is the resovoir for the float valve. After 25 gallons goes here then it can start filling the tanks.
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Most of the rainstorms here occur during the summer monsoon season. This feast or famine style weather dictated a more elaborate storage system. I ordered 3 3,000 gallon tanks and placed them down hill from the house. The system will now hold 10,200 gallons of rainwater. That is what it takes to hold me through the dry season.
Here I am just after getting the tanks in position these tanks hold 9000 gallons.
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After repairing broken joints and having lost thousands of gallons of water, i came up with this solution. the PVC glue just wouldnt hold after repeated freezing and baking weather. no more glue, springs allow movement.
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This valve limits the water pressure in the drain pipe and eliminated leaks in the expansion joints.
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Water draining down from the catch tank to the main tanks. Here you can see that they are nearly full. about 9200 gallons are in the main tanks when they overflow.
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one tank has the inlet, the other two are connected and run out and away from the tank. this keeps it from spilling over and eroding the ground around the tank.
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In spring, I am looking forward to the the next monsoon with near empty tanks. If you are sitting for a long time with a tankful of water and nowhere to put more, You are not using enough or hauling in too much. You should always have room for at least a few inches or rainfall before considering hauling water in to avoid losing the rain to the overflow. I havent hauled water since 2002. Before that i didn't have enough tanks to take advantage of the monsoon.
I placed the 1550 gallon tank near the the corner of the garage where a 4 inch pipe that travels the full perimeter of the house and then across the back of the garage where the garage downspout ties into the 4 inch pipe. It takes 1 inch of rain to equal 1000 gallons with a 1600 sq. foot roof. don't go out and measure your roof because it is sloped.. measure the amount of ground it covers, no matter what its shape.
On My system, before it gets to the tank, the water enters a 'roof washer' this makes sure that the first 25-30 gallons of water dumps on the ground, this gets most of the dust and pine needles before making it to the strainer- without the roofwasher the strainer would be quickly clogged with debris. You should size the roof washer to dump 1 1/2 gallons for every 100 sq feet of roof area.
I designed My own roofwasher using a trash can as a resevoir and the bottom a 5 gallon bucket as a float. As the trash can fills with dirty water the float moves up to block the outlet. The water then backs up and spills over into a 3 inch outlet.
I inserted some common roof flashing into the "T" to raise the water level in the pipe approx. 1 inch. after the rain stops, the trash can will drain trough a small hole near the bottom. Once the trash can drains the valve opens and the 5 gallons or so trapped in the pipe will drain out.
I believe this design is better than the ones sold on the internet. Electronics and tiny valves freeze up or fail. Keep it as simple as possible.
The strainer is a common pool 'leaf skimmer' that you would clean a swimming pool with.. $5 at wal-mart. The 1550 gallon tank has a hole bored in it at the 900 gallon mark where i attached a 1 1/2 PVC pipe that then goes underground and under the driveway and downhill to the large storage tanks.
Inside the first 3000 gallon tank is a filter from swimming pool filter. this catches anything that managed to make it through the first filter. the 3 tanks are perfectly level to one another and are connected at the bottom, the water fills all 3 equally. This manifold pipe is buried under 2 ft of dirt to prevent it from freezing. two of the tanks are attached at the top and drains down and away from the tanks when they overlow. Without this, the water would pour out and erode the dirt and stone the tanks are sitting on...plan ahead!
The 600 gallons above the outlet in the small tank serves as a buffer for the occasional cloudburst. I have seen it nearly fill up but that was a very unusual downpour. Once a day a timer turns on the pump at the main tanks and runs for 6 minutes, topping off the small tank to the 900 gallon mark. The timer is adjustable from 1 minute up to several hours. I experimented with how long I needed on average. If it pumps a few too many gallons, it simply runs back down to where it came from.. no water is lost this way and no water sits in the pipes where it could freeze. The timer is set for 1 PM when I am not at home but the sun is usually already topped the batteries off and there is plenty of power that would otherwise not get used.
I can switch off the outlet that powers the timer to keep it from pumping if I am away on vacation. I am sure its not the perfect system but it works.
Here is the southwest water is becoming more of an issue every year.
According to what I read, the average person uses about 250 gallons a day.. this is crazy.. I can get by on 25 gallons a day without much trouble by using my Staber clothes washer, low flow toilet and low flow shower head.
I can be reached via email, at:
solarman@netmdc.com
Copyright 2004, greenmountainsolar.com
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