Rainwater Collection and Distribution

Print Friendly, PDF & Email

The Bottom Line


  • One of our first goals after relocating to Florida from drought-stricken Northern California was to design and install a rainwater collection system. We captured runoff from every inch of roofing and piped it underground to front and rear pumping stations and tank banks.
  • Modular components, balancing valves, a 2” distribution system, and a 1-hp pump were employed to get the job done. The verdict? We can now water all of our raised beds for up to 45 days without rain. Our plants have been thriving for seven seasons.


  • Rainwater doesn’t contain any chemicals.
  • City water is expensive. Rainwater systems save money.
  • Maintenance is limited to any pumps you may be using for distribution.
  • Unlike a water well, rainwater systems can’t be contaminated by anyone but you.
  • Capture can easily be bypassed when your tanks are full (simply disconnect the downspouts).
  • Lifespan is typically unlimited; adds value to your property, especially when leveraged with other features such as a garden.
  • Provides a secondary source of drinking water in emergencies (must be boiled, treated, filtered, or purified).


  • Takes up space; pumps must be maintained; gutters and downspout filters must be kept clean.
  • Capture should be bypassed during power outages to prevent swamping of sumps (and pumps); this can be mitigated by installing an emergency power supply (such as a Generac whole-house generator).


  • About $1.5 per gallon if you do the work yourself.


  • Water is the new oil. Shortages are increasing daily. Rainwater collection and storage ensures that water for you and your plants will always be available.

Rainwater systems for gardens are relatively easy to design and construct, especially if you do the work yourself. The design shown here uses a combination of above-ground and underground piping and is constructed from off-the-shelf parts. Use a strainer filter to keep leaves and debris from clogging up the system and damaging the pump. The hard part was tunneling under the carport to install the 4″ collection pipes. Total cost for a 5000 gallon system is comparable to that of installing a well, so consider your options carefully. Distribution of the collected water can be pressurized or gravity fed. Gravity systems are ideal for small gardens but will prove inadequate for anything larger. Starting at about $300, pressurized systems require a pump, a pressure switch, a pressure tank, and other components.

Ref=2014, F:2016_1016-EBG Newsletters2017_0310-issue 4/Rainwater-Collection-Design-a.jpg

The initial design for EBG is shown above. Modular components, balancing valves, a 2” distribution system, and a 1-hp pump were employed to get the job done. The verdict? We can now water all of our raised beds for up to 45 days without rain. Our plants have been thriving for seven seasons.

Constructing the Front Tank Bank Enclosure

The design finished, it was time to begin the installation of the front rainwater downspouts, drains, and pumping station. We would also need an enclosure to hide the front tank bank. The tanks, the enclosure would also provide privacy for the carport and front patio.


Installing the Front Pumping Station


The photos above show the downspouts connecting to 4″ PVC pipes that channel the rainwater to the front sump pump.

Downspout to Collector Connection

How it works: The original downspout (left photo above) uses a flexible plastic accordion fitting to funnel the rainwater into the 4″ PVC collector pipe that channels the rainwater to the front sump pump. The photo at right (above) shows the accordion fitting removed to reveal the downspout filter.

Downspout Filter Testing


Testing of the often-recommended first flush system (shown behind the Zinnia flower above) for keeping debris out of the rainwater tanks produced unsatisfactory results. Although effective for removing the granular debris that sluffs from composition roofing shingles, it doesn’t stop leaves, because leaves float! Our new three-layer strainer outperformed the first flush system (shown above). Best of all, it’s invisible when installed. And, after several years operation, we had no problem with sludge buildup in the system or sump.


We spent lots of time designing an overflow method (above) only to discover that it was much easier to simply disconnect the downspouts that feed the sump pump.

Installing Rainwater Collection Piping


The image above shows the piping system for the front section of the rainwater collection system. We used the lifting hooks (created earlier) to lift out the pavers that would cover the pipe trenches. The piping system uses a “flipper floor” approach like that found in data centers to provide access for maintenance.

The Front Tank Bank Enclosure


For the front tank enclosure (above), we used vinyl fencing panels reinforced with 2″x3″ extruded aluminum rails. The rails were filled with pressure-treated timbers that were cut to length and pressed into place to fill the internal void and provide additional stiffness. This design allowed us to mount the fence panels to the rails (instead of the 4×4 posts) to make it easy to remove these panels later, to service the tanks of the front tank bank. The rails also provide support for a supplemental solar generator system that may be installed later.


With the enclosure nearing completion, it’s time to determine the best height for the IBC storage tanks (to provide optimum head pressure). We had hoped to use head pressure to feed our irrigation hoses, but that approach proved insufficient as our garden grew in size.

IBC Rainwater Tank Test


These photos show the first tests of the IBC totes that will store our rainwater. In addition to head pressure, we tested different options for filling, draining, and removal. The 2″ pipe at the bottom left (above) is the fill pipe connecting the sump pump to the top of the tank.

The 2″ pipe at the bottom right (above) is used to drain the tank.

The photo above shows a temporary pipe for draining the tank down the driveway. Prior to installing the concrete and constructing the rainwater system, we re-graded the property to remove low spots and redirect water flow away from the house.

Rainwater Distribution Pipes 053115

The enclosure complete, 2″ PVC pipes were installed to distribute the rainwater from the front tank bank to the rear of the property (the top pipe running under the driveway in the photo above). The vertical pipe (shown capped in the photo above) was installed for later use. The pipe in front (running to the left of the photo above) is the ‘waterfall’ overflow, initially thought necessary to prevent overfilling the tanks.


Several “bucket filling stations” were installed (in the initial design) to distribute water to the first raised beds.

After passing under the driveway, the rear distribution pipe (above) branches to form two lines; one (shown attached to the fence) for “bucket filling stations”, and the other (running underground along the driveway) that connects to the rear tank bank at the back of the property.

Several “bucket filling stations” were installed (in the initial design) to distribute water to the raised beds. The spigots on each side of the 2″ valve (above) are for distributing water to the individual beds (shown on left and right).

The front tank bank (1500 gallons) is smaller than the rear tank bank (5500 gallons). The distribution system allows us to transfer rainwater from the front tank bank to the rear tank bank for storage. Our capture roofs in front are twice as large as the capture roofs in back, so the front tank bank fills quickly. The ability to transfer from front to back has proved very effective.

Distribution piping from the front tank bank (above).

Photographs and careful documentation help us to remember how the system was constructed. It also helps to identify unnecessary elements of the design.

Front Tank Bank Enclosure 062315


The images above show the front yard after the front tank bank installation (within the enclosure) and before the front raised beds (and solar) were added.

The overflow pipe in the front yard (above).

Rainwater Distribution Front 101615

Except for the 2″ line connecting the front tank back to the rear tank bank (the horizontal pipe at the left of photo 14 above), this plumbing (the riser with boiler-drain faucet, the black-capped pipe stub, and the overflow pipe to the front waterfall) is completely unnecessary (sigh).

The elbows in photos 16, 18, and 19 (above) feed the original overflow system (later unnecessary) that directs excess rainwater into Raised Beds #10 and #11.

Tunneling for a New Soaker System 100717 moved to 2 pages

The hardest part of installing a new soaker system is adding the new plumbing—especially when you need to tunnel under a driveway. Thankfully, we have lots of practice! We used a 30′ water boring pipe (above) to tunnel under the driveways. With practice, the tunneling task only takes about an hour. Note the new 1″ pressure-line (attached to the fence above the raised beds) installed to feed the soaker hoses in each bed.

We chose a soaker system over a drip system because it’s cheaper, easier to maintain, and easy to reconfigure. To provide an even amount of water to the bed, each soaker hose should be less than 50′ long; anything longer results in dry spots in the middle of the hose run. Our 1-hp water pump produces 55 pounds of pressure and allows us to supply rainwater to 9 beds (40 sqft each) simultaneously in 30-40 minutes. To anchor the hoses in the beds, we made 10″ ground stakes from medium gauge wire for about 8 cents each. We added quick-connect hose spigots to each bed so that we can attach a short hose for hand watering.

Update: Though we kept the quick-connect hose spigots (on the pressure line), we abandoned the soaker system in 2018. Why, because it uses twice as much water as hand-watering, and the (above-ground) pressure line is difficult to maintain. Tip: Hand-watering allows us to continually monitor the health of our plants on a daily basis. Any blight or bug problems are spotted quickly, before they have a chance to spread!

Raised Beds #1, 2, 3 moved

Rear Rainwater Collection and Distribution System 071515


The 4″ collection pipes in the rear yard are buried underground (below). Some of these pipes were installed before the concrete was poured. The arrow (above) indicates the direction of flow to the rear sump pump.

The images above document the configuration of the collection pipes buried beneath the concrete of the rear patio and driveway.

The image above shows the initial ‘rough-in’ installation of a collection pipe. This run was later changed to avoid the septic tank (marked by orange stakes). The following sequence of photos shows the pipe run from the Easternmost downspout to the rear sump pump.

Rear Sump Pump System

It took time to rough-in all of the collection pipes at a proper slope for feeding the rear sump pump.

In our area, tunneling is easy. The 2″ pipe on the left above connects the front tank bank to the rear tank bank. The 2″ pipe on the right above is the fill pipe from the rear sump pump to the rear tank bank.

Sloping the pipes for proper drainage meant that I had to dig deep to position the rear sump pump (above).

The completed enclosure for the rear pumping station is shown above.

A closeup of the rear pumping station is shown above. The concrete blocks will be packed with sand to provide stability. The 2″ pipe on the left above is the fill pipe that runs from the rear sump pump to the rear tank bank. This pipe runs under the driveway to fill the rear tank bank. The bypass valve and pipe are shown coming out of the top of the pump.

The photo above


The first test of the rear pumping station is shown above. The rear tank bank was not yet constructed so we opened the bypass valve to pump the water into the yard.

An unexpected challenge with the collection system was designing a method for offloading surplus water (from the sump pump) when the tanks are full. Our initial solution was a “waterfall” (actually three waterfalls). Click here to see one of the rear waterfalls in action. We later learned to simply disconnect the downspouts when the tank banks are full.

Rear Rainwater Piping to Tanks 072915

Installing the Rear Tank Bank


The photos above show the rear tank bank under construction. We underestimated the amount of settling under load (when full, each tank weighs just about a ton), and we mixed small (270-gallon) tanks with large (330-gallon) tanks, which complicated plumbing. And we made no provision for tank removal or replacement. These problems and more would be solved in time.

Rear Tank Bank Rebuild Project 121519

Wrapped in black plastic (above left) and plumbed with 2″ PVC piping, the IBC totes in the rear tank bank are covered with Ondura panels that are strapped in place. The rear door of the shed is shown in the photo above.
Hidden behind the shed in a line along the West fence line, the rear tank bank is stacked on concrete blocks at a height 8″ inches taller than the front tank bank (to assist transfers from back to front).
The front portion of the rear tank bank is shown at left. Note the 4″ fill pipe from the shed roof gutter, the 1.5″ fill pipe (from the sump pump), and the 2″ overflow pipe (drains to the driveway).

The back portion of the rear tank bank is shown above. The front portion is shown in the image below.

Original design flaws: The original design of the tank banks had a few problems. First, it was impossible to remove a single tank (for repair) without removing a large portion of the Ondura covers. Second, the Ondura covers were strapped in place, and had to be removed to open the tank lids to allow cleaning.

And, the IBC tanks were installed in order of acquisition. Because some tanks are larger than others (330-gallon versus 275-gallon), the installation order resulted in a mixed layout; the large 330-gallon tanks were mixed in with the smaller 275-gallon tanks, complicating the plumbing and fill/drain performance. Finally, the Ondura panels offered poor insulation.

The first step of the rebuild project was a shopping trip to buy concrete blocks, pavers, roofing panels, and PVC fittings. These supplies were expensive, but we saved a ton of money by doing the work ourselves.

In the next step, we extended the paver base to provide a solid foundation for the new configuration.

The large 330-gallon tanks are shown in the foreground.

After removing the plumbing, we (again) used ramps to dismount the tanks from their original configuration. The tanks are not heavy, but they’re old and quite fragile. Note that each of the tanks is wrapped in black landscape plastic to prevent algae growth.

Ramping the Tanks (from 062316 Chronicles)

After lots of work, we finally had the tanks in place, plumbed, and covered again. This time we used styrofoam sheets to insulate each of the tanks, and we added a removable top cover to make it easy to access the top lid of each tank (for cleaning).

Two tanks were damaged during the project; one developed a seam leak around the drain spout, the other was accidently punctured while installing the outer cover. The new design proved useful in that were able to remove both tanks by opening the top covers and lifting them out with a block-and-tackle rig.

We used JB Weld Plastic Bonder to repair both leaks (works great on HDPE plastic!).

Replacing the tanks was easy. We used a 2×4 board (during re-insertion) to keep the valve from hanging up on the cage frame as we lowered the tank into place.