The single biggest mistake when harvesting rainwater is to NOT do it at all. If you don’t harvest rainwater, you are missing an opportunity to collect a vital resource that is being delivered to your house for FREE. Even if you are on city water or have a well, harvest rainwater too and water your plants with it because it is higher quality water! If you have no other source of water on your site, you must harvest rainwater so please read on.
The Design Process
Let’s start here with these videos. Both households depend exclusively on rainwater as their only water source and both guys do a great job at walking through their systems and explaining how the components work. Roofs, gutters, debris excluders, tanks, valves, pipes, filters, pressure components and final treatment are links in a chain of the whole system that brings water to our homesteads.
The following guidelines when designing or upgrading your water catchment system will help to keep the chain connected and the water flowing:
- Collect the highest quality water. Follow the Treatment Train to keep contaminates out: prevention, exclusion, sequestration, filtration, inactivation
- If you plan to use your rainwater as a back up to Study Butte or Lajitas water there are specific regulations to consider up front.
- Yes, you can drink rainwater if you keep it clean and filter it, it tastes wonderful.
- Plan for future expansion
- Gravity is energy free and works! Pumping water uphill is wasteful of energy and will reduce the lifespan of your pressure components.
This 9,000 gallon system uses metal gutters to collect rainwater from the roof and is stored in 3- 3,000 gallon Wylie tanks each with an independent overflow. Outflow plumbing consists of Banjo Valves, PP reducing fittings, compression fittings, hdpe pipe and brass components for longevity. This piping is later buried. A top side hose bib allows for access to water at the tank as well as complete drainage of lines. Each tank can be isolated for maintenance without draining the entire system.
Financial Incentives
The state of Texas encourages rainwater collection by making it sales tax exempt. Section 151.355 of the Texas tax Code exempts all rainwater harvesting equipment and supplies from state sales tax. To claim this exemption, the purchaser must furnish a Tax Exemption Form 01-339 to the supplier at the time of purchase.
Click HERE to fill out your sales tax exemption form
Building Your System
For the DIY, all of the materials you need for a long-term, low maintenance system can be purchased locally or online.
You can’t throw a rock out here without hitting a welder so your collection structure should be easy enough to get built by a local. The size of your collection surface determines your storage capacity. Square footage of roof x .62 = gallons per inch of rain. Familiarize yourself with local rainfall: Rainfall Patterns in Terlingua Texas.pdf
Wylie storage tanks (the black ones) are trucked in locally by All Energies 432-244-7656 terlinguasolar@gmail.com or you can also purchase Enduraplas tanks (the tan ones) from Outwest Feed and Supply in Alpine. Water cubes or any other white or clear plastic tanks used for long term storage will grow algae and they will not last many years but they can be used for garden water if kept seperate from your house system.
You need a solid base for your tank that is level, compacted and free from pokey things. It does not have to be concrete but can be. Most tanks will be just fine on the native compacted soil after raking or removing the rocks and sticks. If you need more material to create the base, A word of caution here on ordering a truck load of sand for your base. There are local sand dunes that are mined primarily for use as a masonry additive. It is a fine, clean, dark grey sand that is easy to get and when dumped out looks like a superior product and it is for a lot of cases. However, it has been deposited over millennia by being blown by the wind and that means it does not compact into a sturdy base. If you need to get material hauled in, there are better choices like road base or creek bed sand. Talk to the person hauling your material about what you don’t want (ie. no stucco sand aka. black sand)
On your tank you will have a 2 inch bulkhead and it needs a 2 inch Banjo valve on each tank. No PVC here! This is the first and most important link in the chain! Banjo valves are more expensive than PVC but they are built to last and the seals can be replaced when needed.
Protect the system from freezing.
If you have exposed pvc or copper pipes they will freeze and break, guaranteed. Insulate those pipes!
Use a valve cover and the rest of the pipes can be buried. 6 inches of dirt is all you need for your pipes to survive a “normal” desert freeze.
In case of exceptional freeze (ahem, 2011) here’s a tip from Dan P:
“If you have the electrical capability, wrapping the outflow valves and any other exposed pipe surface in heat tape, followed by insulation, provides peace of mind, although there’s always the possibility that the power will go out.”
Beyond the valve you have several options. PVC is an available and economical choice but since these components are susceptible to breakage from freezing and uv degredation, not adaptable over time and are environmentally toxic to manufacture, I personally go as far as we can beyond the valve to avoid it’s use.
My preferred pipe material is HDPE pipe (a.k.a fast line) for the superior quality and longevity of the material, no plastic can beat it. Buy pipe from Outwest Feed and Supply in Alpine and fittings from HDPE Supply. Compression fittings first, they are more expensive than locally available barb and hose clamp fittings but they also are extremely reliable. Watch the video below to see how to use these fitttings.
Another option for connecting fast line is socket welding. The welded pipe is the most secure attatchment for hdpe pipe. Outwest Feed and Supply in Alpine sells the weld fittings and has a welder available for rental for a very reasonable daily price if you want to go that route. I can also weld hpde pipe.
A few more things to note about putting all of this pipe together
- Draw your system out and count all of the elbows and tees you will need
- Where the valve connects to the pipe, use a removable fitting such as a compression fitting or union so each tank or valve can be removed and serviced without disrupting the rest of the system.
- A good idea is to add a hose bibb connection on the top side and bottom side so you have hose conections for a drip system, or moving water from one place to another, or shutting the system down and evacuating the line if needed.
Pump, pressure tank, filtration and treatment are the final links in the chain. There are many different factors to consider in choosing these components and the depth of that topic will be covered in future articles. If you feel like you need professional help building your system I’m here to help! Please schedule a call or you can also call Keen Contracting on the finishing components and interior plumbing.