Dual Feed Rain Barrels


Feb 25, 2010

My wife is an avid gardener and always wanted some rain barrels. After we moved up to Milwaukee we thought that was the perfect time to try them out. The new lot was twice the size of the old one which meant we could do a lot more gardening and would also be using more water. Aside from the environmental benefits we figured the rain barrels would be a way good way to offset the water bill a little.

Additionally, one particular feature we noticed immediately about the house was the heavy clay soil. Heavy meaning you could sculpt a pot straight out of the ground. A side effect of that is that water around the basement of the house didn't really drain away well. The house has two sumps and in the spring they both ran quite frequently. My suspicion was the drain field didn't have enough of a slope to carry the water away. I dug down to the pipe along the house and it seemed like the pipe was always half full. I would expect some standing water but that seemed like a bit much.

So when decided to install a couple of rain barrels we had the thought of feeding them with both the downspout from the roof and the outflow of the two basement sump pumps - a dual feed rain barrel system.

My theory was the dual feed system would provide two benefits. First, the sump pump would provide more water for gardening. Second, the sump pump water would be diverted away from the drain field and less of it would constantly cycle between the pump and drain filed.

Research on Sump Pump Fed Rain Barrels

While there was a lot information on the web regarding rain barrels in general there wasn't a lot on on the idea of pumping sump pump water into a rain barrel. My biggest question was how safe it was (bio hazard wise). The few post I did find on the subject didn't mention any series problems with the idea.

I was worried about the cleanliness of the sump pump water. I don't mind the occasional smashed thumb or scar due to my own home improvement projects but I was rather concerned about the possibility of accidentally poisoning my family. I am well aware rain barrel water is not potable but considering very few other people were doing this I thought there might be a good reason.

Then I considered that the water from the roof contains all sorts of bugs and bacteria (i.e. birds can do there business wherever they want). The basement water was at least semi filtered due to seeping through 8 feet of clay. Also the sump pump water, at our house anyway, really wasn't all that stagnant as the pumps seem to run at least once every couple of days, even in dry times.

The worst issue anybody on the web could think of was the sump pump water might be too full of particles and clog up the pipes. A quick look at the two pumps in my basement did not prove that out. The water was quite clear and I could see the bottom of the pit at a depth of about a foot and a half.

Rain Barrel System Parts

A local Milwaukee based company called Growing Power had the rain barrels for sale at $40 a piece at a local market. The barrels were old soda drum containers and were very sturdy. The picture of the barrel here was taken in my basement after the barrel had been brought in for the winter so its a bit dirty.

We wanted to be able to easily fill buckets from the rain barrel so we decided to construct a base that elevated the barrel by a foot or so. For the base I figured the easiest design that could hold up to the weight 55 gallons of water would be stone. I took a walk through the landscaping department at the local hardware store to see what the options were.

After pricing out the required number of decorative blocks, which added up to over a $100, I opted for the cheaper solution. Basically I bought three prefab concrete blocks ($5 each) with a set of four 12" square paver stones ($6 each) per barrel. The general idea was that the 10" cement blocks would provide the height for the base.  The paver stones would make it look a little nicer and create a flat surface on top of the concrete blocks to put the barrel on.

I would have bought one, large solid stone for the top but none were available that were large enough. The combination of the smaller ones worked well enough and being smaller they were easier to transport.

The pipe fittings (faucet and run off tube) on the stock barrel were only secured by RTV. We planned on heavy use of the system so I planned on upgrading the fittings on the barrels using some two part epoxy, available at any hardware store.

For the pipe fittings I went with gray PCV pipe fittings mainly because they were an inexpensive option at less than $1 apiece. For the inlet I used 1 1/4" fittings and the for the output I used 1

1/2". I wanted a larger output than what the barrel came with because I was worried they smaller one would not keep up during a heavy storm (that and I like to tinker with things). It would not be a huge deal if the overflow rain water leaked out around the downspout once in awhile but if it happened on a regular basis I thought it might erode the base of the barrel.

A cheap source of hoses in these sizes are the sump pump hose kits. You get about 20' of hose for around $8.

I bought a bag of standard hose camps to clamp the sump pump hoses to the PVC fittings.

Rain Barrel System Construction


The main construction component as far as modifying the barrel is what glue to use for the pipes and hoses going in and out of the barrel. As I said above, the stock RTV secured fittings the barrel came with were not really strong enough in my opinion for heavy use.

I picked up a couple of different flavors of two part epoxy from the local Menards. The plastic bonder and weld epoxy both seemed like good choices: weatherproof and worked on plastics.

Sump Pump Inlet and Run-Off Outlet

The key idea on the sump pump inlet is to have it enter the barrel at the very top above the run-off inlet. The sump pump water will fill up the barrel to the bottom of the run-off outlet.

My thinking was to keep the hole of the inlet an inch from the top of the barrel so it would not effect the mechanical structure of the barrel. Then I put the outlet hole so the bottom of the outlet was one inch below the bottom of the inlet.

When I happened to buy the epoxy for this project Menards only had one of each type (plastic bonder and weld) so I had to use different epoxy on each barrel. The plastic bonder is the yellow-ish clear type, the weld epoxy has a gray color (pictured on the left). I think if I had a choice I would go with the gray weld epoxy. From its description it seemed more appropriate to what I was trying to do.

Repositioned Run-Off Outlet

The barrels came with a pre-installed run-off outlet. However I wanted to reposition where the run-off pipe was so all the hoses would be towards the rear of the barrel. I recycled some of the fittings that came with the barrel and bought a cap to plug the holel.

Roof Downspout Inlet

The barrels came with a 3" circular to square downspout but our house had 4" square pipes. The jigsaw made short work of enlarging the opening. The barrel's top was made with just enough margin around the original 3" opening to make it bigger.

Another good modification for the top of the barrel is to add some drainage holes. The outer top seem is sunk down slightly from the rim of the barrel. That seem created a small pool on top of the barrel which makes a perfect mosquito nest and makes the barrel messier. I used an 1/8" bit to drill diagonally from the bottom of the seem to the outside of the barrel. I spaced the holes about 4 inches apart all along the rim so if one hole gets plugged up there are plenty to spare.

Drain Faucet

The barrels came with a reasonable faucet but I thought it was a little short. For my barrels I knew we were going to elevate them so we could fill buckets so I wanted a longer shaft.


To prep the ground where the base was going to be built I first dug down about a half foot. I filled this hole with a layer of rocks. On top of the rocks I put a bag of quick-create instant cement (recommendation from my dad). Then I placed the blocks on the quick-create and rocked them back and forth so they would sink in slightly. The idea was that when the moisture eventually activated the cement, having the blocks slightly seated would make them more stable.

After all three of the cement blocks were roughly level and at equal height I arranged the four paving stones on top of the blocks. I didn't secure the paving stones to the blocks. I figured the weight of the bricks themselves and the barrel, even when it was drained down to the faucet, would be enough to keep them in place.


For the primary downspout connection from the roof its the same as a standard rain barrel. Connecting the downspout from the roof is pretty straight forward.

For the secondary sump pump connection I realized I needed a very water tight connection up to the inlet of the barrel. My first attempt at the piping leaked. Every time the pump ran whatever water was left in the pipe would leak out which made the ground around the barrel rather spongy. A few hose clamps and changing the RTV fittings to epoxy fixed that problem.

Dual Fed Rain Barrel Usage Notes

Initial Modifications to Barrels

When we first started we were going to simply use watering cans to transfer water out of the barrels. That is why we spent so much time/money on the elevated bases and extended faucet. But after the first week or so we noticed that every time a watering can was filled there would be the inevitable spill. The clay soil around the barrels would not let the spills drain away quickly enough so the area around the front of the barrel became a mud pit.

Our solution to this problem was attaching a hose to the faucet. The hose eliminated the spills plus the water could be delivered anywhere in the yard somewhat automatically. Just place the hose in a flower bed, turn on the faucet, and go take a break while the hose did the watering. The pressure was not very high but it was enough.

If you do opt for a hose for your rain barrels make sure you mark it so you know the hose is not to be used for drinkable water.

Summer Water Capacity

The secondary feed of the sump pumps into the rain barrel really extended the usable volume of water we could get out of them. One benefit of the clay soil around our house is that it drained very slowly and which I think acted like a big underground sponge. After a storm the pump's cycling frequency would be noticeably higher for several days. Long after the original 55 gallons were spent the basement pumps kept the barrel full, sometimes for as long as a week.

We did discover that toddlers love the rain barrels (which scared the hell out of me due to the salmonella threat). Adding the hoses to the drain faucet removed the fun of playing in the water. Plus we setup the kiddie pool in the back yard, filled with tap water, to distract them. Another option I discovered later was you can buy faucet locks at the hardware store which have a key.

Winter Storage

I brought our rain barrels in for the winter. For standard single feed rain barrels some people say you don't need to do this. With our dual feed system we had to make sure the sump pump piping would not freeze during the winter (we live in Wisconsin). In our system the inlet hose to the barrel is always full of water and it is exposed to the elements with no insulation. If the inlet pipe freezes the pump would not be able to do its job and our basement would eventually flood.

My solution to this was to disconnect the barrels and route the sump pump outlet directly into the drainage pipe. I built some cedar covers to put over the pipes as added extra insulation. So far it has worked through this winter with no problems.