Water Collection System

Here’s the plan for our water collection system. Red circles are down spouts. The blue circles are rain tanks.

We finished our water collection system in mid March just in time for our spring rainy season. Check out previous posts about installing the rain water tanks and gutter below.

Water Tank Install

Gutter Install

The last step of the process was to set up a system to convey the water from the gutters into the tank. There are two types of water conveyance systems, dry and wet. With wet systems gutter down spouts feed rain water into pipes that go straight down into the ground. These pipes are all connected underground and run to the tank where they come up out of the ground and into the tank. In this system the pipes never drain out staying full of water (up to the current water level in water tank).

With a a dry system the gutter downspouts feed into pipes that are suspended above the ground and eventually go into the water tank. The pipes in this system drain out completely after it rains thus a “dry system”

Here are a couple of YouTube videos demonstrating a wet and dry system.

Wet System

Dry System

We opted for a dry system for several reasons
  1. Short distance and adequate slope between house and rain tanks: For water to flow effectively through a pipe it needs to drop 1/8″ – 1/4″ per 1 foot of run. Over ten feet a pipe would need to drop 1.25″ – 2.5″. Our tanks are around 40 feet from the furthest downspout. So, the pipe under that downspout needed to be ~10″ higher than where water enters the tank. In buying a tank a major consideration was getting one that was not too tall.
  2. No digging: Our subsoil is rife with limestone, roots and heavy clay. Since all pipes in a dry system are suspended above ground no digging is required.
  3. No standing water in pipes: In central Texas we have issues with mosquitoes so I like that the only standing water is in the tank where it is well protected from mosquito incursion. Mosquitoes can be mitigated in wet systems by adding screens are leaf eaters at downspouts.
  4. No sediment/debris collection in pipes: Even with gutter guards some debris gets through and there are dozens of trees around our house that would love to clog up our system. Any debris that gets through our gutters guards flows through the pipes to the tank where it is filtered out by the leaf eater. Debris in a wet system can be mitigated by installing leaf eaters at each downspout. Wet Systems also need to include clean outs where the entire system can be drained.
Here’s a video recapping the build
And here are some stills with more details:

Here’s my work sub-compact. If you ever wondered how many 10′ foot section of 3″ PVC pipe you could safely fit in a Honda Fit I would say six.

Test fitting the first section of pipe

Painting PVC starts with roughing up the surface with sand paper

Then the PVC is cleaned with acetone

Then the spray painting begins

Securing pipe hanger around pipe

Confirming 1/4″ drop per 1′ run slope 

Securing main roof downspout 
Finishing up the water collection system for the west side of the house

Building a shade roof. Securing the purlins in the middle of the structure was a bit of a stretch

I also added gutter guards to all the gutters

The finished tank shade roof

In this section I wasn’t able to slide the gutter guards underneath the roof. In retrospect I should have installed the gutter guards when I first installed the gutters

The is the main roof downspount on the east side. A section of flexible downspout slides over the downspout opening. Then a gutter downspout/drain adapter slides over the flexible downspout. Then the 4″ to 3″ PVC adapter slides over that. All connections are secured with self tapping screws.

Where all the water sources converge

Down spout connection

Another look at the convergence on the east side of the house. The valve going down will eventually lead to a first flush diverter.

I also tied in the gutter from the shade roof into the system

On the east side I diverted the water from the shade roof to a separate container (275 gallon IBC tote). The reason being that the shade roof is more likely to see animal traffic being in close proximity to the oak tree. 
Rain tank taking on water

You can see the leaf eater filtering out bits that got through the gutter guard.

Jean checks out water flow during a rain storm