GradyBarrels Blog

Two 1550 gallon tanks for rain water catchment.

This has been one of my more complex rain catchment systems to date. My client qualified for a local program called the Lane County Firewise Incentive Program. The program requires homeowners to take steps to create a buffer on and around their property to become more fireproof in case of a wild fire. This includes roofing, siding and green belts around the house. The county awards grant money to reimburse homeowners for “fire wise” improvements. This is where I came to help.

The idea was to catch water off of their barn roof to irrigate an area around the dry (west/ southwest) side of their home. After visiting their property and assessing the situation we came up with an plan to catch water off of the north roof of their barn. We took into consideration roof size, amount of storage needed and conveyance of the water into the holding tanks and out to their yard. The equation worked out well except for tank placement.

View of project from the north.

The property around the barn slopes pretty severely from north to south. The best area to place the tank(s) would have been the south side of the barn. However, this would have placed the tanks well below the target irrigation area and the garden they wished to irrigate via gravity flow. Running sprinklers for the green belt will require a pump, but regardless, they wanted the option of using gravity for most of their irrigating needs. The solution….

Initial concept drawing.

We ended up excavating a nice level area on the NW corner of the barn. This would give us the room to get water into the tanks while still being able to use gravity for most of their watering. One large 3000 gallon tank would have used much more energy, trenching, and piping to get the job done. Plus, it would have been way too tall for the area. Instead we opted for 2- 1550 gallon tanks.

Vertical black pipe is the first flush diverter.

I built the tank pads out of 2×6 pressure treated lumber and a 3″ deep bed of pea gravel. Later I would add another 2″ of pea gravel around the tanks for insulation. They asked me to put up gutters on the north face of the barn and I completed that. Next, I sunk a 4×4 post into the ground and attached it to the corner of the roof to support a custom made first flush diverter. It is very important to have this support as a full diverter can weigh around 100 pounds. Once the diverter fills, the water travels along a pipe to the man hole of the tank. At this point there is a drop in tank basket that screens out most of the debris that the first flush diverter didn’t catch. Between the two, 98% of all debris won’t get into the tank.

Tanks fills from the black pipe coming off the roof.

Then, I tied the two tanks together with a semi-complex combination of valves, elbows and piping. This will allow the tanks to fill and empty evenly. Each tank has it’s own 2″ ball valve to control the water for seasonal rainfall and maintainance needs. I also added a fire hose adapter to one side and a hose bibb for gravity fed watering to the other side. Both tanks combined at a “T” to feed water to the pump.

Tying two water tanks together.

The pump was necessary to run a couple of sprinkler heads in the front yard (the main reason for the project). We also put a 4×4 post near the garden and ran pipe up it to a hose bibb so they had pressurized water for the garden. Because of the distance the water had to travel and the pressure needed to run a couple of sprinklers we chose a 1/2 hp shallow well pump to get the job done. We put a relief valve on the water line to adjust the pressure in case there was a need to step up or down the line pressure coming from the pump. This relief valve, when in use, put the water right back into the tank so not a drop of water was lost.

Pump inside the barn.

All in all, with irrigation line and the overflow pipe (which I will go over next) I ended up trenching about 300′. When choosing a trencher, I advise to rent a nice self propelled one. Also, trenching the dry areas was incredibly easier than trenching the wet areas. The dry areas allowed for better traction of the trencher.

Most important of all was directing the overflow into the proper area and making sure to gets it there quickly. The overflow on these tanks starts out at a 1 1/2″ fitting near the top of the tank. From the collection tank I ran a pipe to the next tank. At this point I immediately increased the pipe size to 3″ with a 3″x3″x1 1/2″ “T” fitting.

Overflow pipe going into the ground and off to a safe place.

This would allow both tanks to empty and combine as quickly as possible. I then took the pipe straight to the ground and into a trench that would carry the overflow over 100′ to the natural drainage of the property. At this point the pipe comes out of the ground and is partially covered by a large building block for protection. Again, the overflow is the single most important part in the whole design.

Not only was this a rewarding project but it was fun too! The physical work was demanding, the brain work sometimes confounding but overall I’d have to say I love what I do .