Green Solar Powered Water Barrel Version 2




Introduction: Green Solar Powered Water Barrel Version 2

About: 30 Year Retired Electrical technician from the Royal Canadian Navy

I am back after my first version of solar powered water tank .

I moved and lost the convenience of my previous system but I have plans for a larger garden this time. The new owners of the house and water system absolutely love it! I decided to replicate and upgrade the design to match the needs of where we now live due to higher summer water restrictions. First thing you need is something to hold your recovered rainwater in. My new design uses two recycled FOOD GRADE water totes of 250 imp. gallons (275 US gallons) each. They cost about $150 each and I easily sourced them though You You can see whats available in your area by simply googling "1000 liter water tote near me". You can get them much cheaper if you don't care about what they were used for originally (lubricant, pesticide etc).

I would HIGHLY recommend that you DO NOT USE ANYTHING OTHER THAN A FOOD GRADE CONTAINER if you are watering plants, animals or storage for consumption. Only use the non-food grade containers to store water for firefighting, pressure washing or similar. The food totes that I've seen are 250 gallons and 300 gallons and all come with an integral valve at the bottom and a fill cap on the top. I'm sure there are other sizes out there but these seem to be the most common.

An important thing to remember is to connect all of your water barrels with a common manifold so that they all drain and fill at the same time if using a single supply source as I have. You can see the white PVC tube between the two barrel outlets that allows both filling and draining at the same time.

These barrels weigh a considerable amount when full, about 4150 lbs for the water alone, then another 140 lbs per tank! Make sure that when you design a stand you consider the surface you putting them on that it is firm enough not to sink, and if you are raising them above ground that you use wood that can support 2 cars!!! Remember that just because it doesn't fall down right away, doesn't mean it won't.....and normally at a time when you need the water really bad or when it can hurt someone or something.

Step 1: Primary Filter From Downspouts

Roofs and downspouts collect all manner of debris and I would prefer it not be inside my water tanks and inevitably inside the pump.

I manufactured a primary filter by using two layers of 1/4" x 1/4" steel mesh slightly offset from each other to create smaller holes. This was then placed over the end of a piece of firewood with the same dimension as the tank top opening, and hammered until it produced a 'bowl' that would fit tightly inside the tank opening but still have a lip and not fall in.

Step 2: Secondary Filter Before Pump

while the primary filter removed the larger stuff like pine needles and leaves, there are things like seeds and other crud that can damage the pump or plug the hose nozzle. So this filter is inline on the tank output to filter all of the smaller stuff. It uses a reusable nylon mesh than catches the small bits and can be rinsed off.

I managed to find this item in one of our local hardware stores here, so don't know whats available in your area. Here is a link for information.

here is the ball valve that I used as a shutoff for both tanks

To enable connection of the tank to standard plumbing sized pipes and fittings I used the following parts to adapt the industrial tank opening down to 1" PVC.

The first part to connect to the output of the tank ball valve is the large end of the larger rubber coupling

The next part goes into the smaller opening of the larger rubber coupling

The next part connects between the reducer and the final 1" PVC piping.

Here is the smaller rubber coupling

Step 3: All Downspouts Rerouted

My new system uses the water collected from two sheds with a roof area of 450ftsq and all four downspouts (two from each roof) are rerouted into a single barrel opening.

The 'splicing' of the downspouts into a single pipe involved a set of small metal shears and a 1/2" drill bit to get the hole started. Once the pipes are connected they need to be held together with small metal screws (designed for downspouts) and a sealant (designed for gutters) that will prevent your recovered water from splashing out of your newly joined non-factory joints.

Step 4: Outlet From Secondary Filter Into Garden Shed

simply a hole in the back of the shed for the hose to pass through :)

Step 5: The Hose Protection Tray

the hose runs along the back wall inside the shed, but may inadvertently have stuff placed on it. To prevent damage or loss of water, I ran the hose between 2x4's as protection.

Step 6: RV Water Pump and Battery

I used a full size car/marine battery in this version of the water system as the volume of water stored is much greater at almost 600 gallons (between the two tanks) if the tanks are topped right up to the top opening.

The water pump is a typical RV water pump with built in pressure switch so the pump is not always running unless the pressure drops when you squeeze the nozzle. This prevents dead-heading the pump (pumping a pressure in a closed system). Keep the consideration of battery size, water volume potentially pumped and current requirements of your pump when considering the pairing of pump, battery and solar panel.

The battery I used , when I bought it was on sale and good reviews.

The water pump I used, no sale but good reviews.

In these photos it does not show all the routed wiring and the protective wooden lid was removed for ease of viewing. Everything was connected as per my hand drawn schematic.

There has been some good dialog in the comments section as to safety when dealing with batteries and for cohesiveness I will restate the important parts below.


Open battery terminals are a hazard if they are in an open area that is potentially subjected to contaminants (liquid or solid) as these can lead to 'tracking' (where the battery finds a minor conductive path) or where they can directly contact a conductive material creating a short (create a current path between positive and negative).

Be careful when connecting to the battery to not short out the battery terminals as this can allow an excessive amount of current and vaporize (yes literally) the conducting object between them, whether this is wire, watch or even a screwdriver and cause burns and fires.

Do not forget that when a lead acid battery charges it produces small amounts of hydrogen gas which needs to be able to vent to outside as it is flammable. Do not smoke around a charging battery!
Do not store or subject your battery to direct sunlight or heat as this can cause your battery to dry out and/or potentially damage the battery case with warping and cracking causing acid leaks.

Any acid on or around the battery should be neutralized with baking soda first and then rinsed away with water before drying.

If you need to top up the electrolyte levels in a non-maintenance free battery, only used distilled water so as not to introduce contaminants into your battery acid and reduce it's longevity. Wear gloves and face-shield if adding water to a battery to minimize the potential for contact with acid.

Use an inline fuse with a current rating slightly higher than the maximum current of the pump you will be using, this will prevent the battery from potentially outputting massive current through the circuitry if a problem was to occur with any component of the system.

Step 7: 40W Solar Panel and Charge Controller

Here is the solar panel I bought that came with it's own charge controller. This is a 40 watt panel and will recharge the battery I selected in an afternoon. For a solar panel it is important to also have a charge controller as it regulates the charge to the battery and prevents damage. The package was on sale for about 90 bucks, and CT often has sales like this so if you're not in a hurry its worth the wait.

For the electrical connections any wire of 14 gauge or larger would be more than adequate. Be extra careful when connecting to the battery to notshort out the battery terminals (create a current path between positive and negative with no load) as this can allow an excessive amount of current and vaporize (yes literally) the conducting object between them, whether this is wire, watch or even a screwdriver and cause burns.

The circuit will function without an inline fuse, but can be dangerous should a short occur with the pump, wiring or switch. So for safety safe use an inline fuse with a current rating slightly higher than the maximum current of the pump you will be using. These can be picked up at any hardware or Canadian tire store.

I have included a sketched schematic of how to connect all the required items. Always follow the manufactures directions for connecting the solar panel and charge regulator as there can be slight differences in connection requirements. My drawing is a guideline. The important things to remember are to fuse the input supply from the battery at a slightly higher amperage than the maximum your pump can draw and to follow that with a switch before the pump. This is important as if you have to work on the pump for whatever reason you can shut off the supply voltage and remove the possibility of a short.

I ended up making a custom bracket to hold my panel away from the side of the shed and at about a 30 degree angle from vertical, aiming south to catch the afternoon sun.

Here is a link for the inline fuse.

Here is a link for the solar panel and charge regulator.

Step 8: Outlet From Pump to Hose Reel

Simply a hose reel that I found and liked.

No photo of the spray nozzle, so use the one you like :)

Here is the one I used.

Step 9:

Step 10:

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86 Discussions

Awesome, excellent build and instructable! I install greywater and rainwater systems for a living so I love seeing stuff like this. My only suggestion would be to paint the tank to make it light-proof (or use an opaque tank). The white tanks are translucent, and any light will eventually lead to algae growth. It's not really a problem or health concern, it's more aesthetic - the tank walls will get covered in green slime.

3 replies

The slime thing is puzzling. I have a 700 gallon tank that I bought from the local farm co-op years ago for use as a rainwater cistern. It's translucent white polyethelene, and I expected algae growth and therefore prepared to paint it to block light. But before I got around to the painting, I noticed that there was very little algae, certainly not green slime covering the walls, so I've left it natural. It sits at the western end of my house and is shaded most of the day, but it still gets lots of light and some direct sun.

My rainwater collection system is still a work in progress, and I haven't yet devised anything I'm happy with. But the cistern has gotten good use for temporary storage of water from the backyard pond when it's time to clean it. The pond gets some string algae every summer, but that doesn't seem to grow in the cistern. The mysteries of algae!

You can see what I'm talking about at


I have plans to close in the tanks at the end of summer with basically a mini shed :)

Perfect timing, we are in BC, Canada and just hauled 4 of these to our new home today :-). Quick question, when both tanks are full, is there an overflow that I missed, or do you just move the down pipes? We have a lot of rain, usually up to June then nothing through the summer. I think there would be times in the rainy seasons when I would get to overflow. Thanks for posting, super helpful.

Just wondering if I am missing something as this instructable seems to end abruptly at the end of Step 8?

1 reply

I figured that I didn't need to include a photo of the spray nozzle as that would have been the next photo (if I included it), so no you didn't miss anything :)

The translucent poly tanks used here may degrade rather quickly (less than 5 years - due to your latitude, your mileage may vary) by crazing from sunlight and cosmic rays. Enclosing them in wooden boxes or putting them in a small storage shed will lengthen their useful time considerably.

3 replies

My above-ground translucent poly cistern has been in place for over 15 years with no sign of crazing. It was made for farm use, so perhaps it's a more UV-stable poly.

You'e quite right. Recycled polyethylene (or other recycled plastics)
can consist of a high percentage of degraded short-chain molecules which are more inherently unstable than virgin polyethylene. The addition of recycled poly to virgin stock can also increase the amount of fugitive catalyst in the plastic, which promotes degradation. Good quality virgin resin from a reputable manufacturer makes for superior products, as can be said about any manufacturing operation.

Good point and I was thinking along the same lines. I will be using some of the leftover metal roofing from the gardenshed build and making a 'mini' shed around the water barrels at the end of the summer.

If you are keen to keep the quality of the water as high as possible then excluding light from the tanks will discourage growth of stuff in the water. One effective way of keeping light out is to bury the tanks. Buring the tanks will also keep the water at a more even tempreature. I have read that using copper rainwater goods (gutter and downpipe) helps to sterilise the collected water

4 replies

Unfortunately these tanks are not designed for burial. The type that are cost significantly more. As for copper, I'm not sure as to the cleansing properties but it would not be cheap :)

Copper is toxic to algae -- and to fish.

Yes, I admit my comments are more aimed at the theoretical ideal installation. I guess that using these tanks you would have to build an underground enclosure with a concrete load-bearing roof. (not simple or cheap)

here was another good source for rainwater harvesting I found.

1 reply

Good idea, and I am considering that as a component in the new filter