A Guide to Using Rainwater for a Water Source

rainstorm in Big Bend

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.
rainwater collection tanks and plumbing

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)


If you feel like you need help building your system I’m here to help! Please schedule a call


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. You can buy online at the link above or call me at 432-371-2501 to get one. The hardware stores do not carry these valves and although Outwest Feed does, it will be the most expensive route.

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.

Working with greywater sources

Greywater is defined as water that has already been used in a household water supply that does not come from the toilet. (Toilet water is blackwater) Water from sinks, showers and washing machines qualify as greywater. It is too dirty for people and pets to drink but not too dirty for plants to drink as the plants are able to filter out the nasty from the water and just use the good stuff. A properly designed greywater system in essence, is a biological filter for your home’s wastewater.

Creating a greywater distribution system can be very simple. A bucket under a handwashing sink catches the draining water, at the end of the day you take the bucket out and dump the water onto a tree. That’s it! The concept relies entirely upon redirecting the greywater that would have otherwise ended up in a wastewater system onto a secondary source such as a shade tree, that can then add further value to a home.

But it does not stop there, the concept can be refined and elaborated upon to create a system that works time and time again without any additional user input and requires minimal maintenance. These are the systems that I design and install and it just takes a little more information from the basics to get there.

Construction of wetland for cleaning and distributing high amounts of laundry water
Construction of wetland for cleaning and distributing high amounts of laundry water

Important Safety Considerations

First off, greywater is only one step away from blackwater, ie. poo poo water, so we need to address and understand some health and saftey concerns and state regulations before beginning the design. Texas is not a highly regulated state but there are in fact, state regulations regarding the distribution of greywater, mostly regarding spetic tank sizing. That should tell you something right there about the importance of a correct design. The State of New Mexico also has some additional regulations that are worth reading as they are more specific about the actual practices of using the greywater.

An interesting point to note about Texas and New Mexico regulations is that a common source of greywater, the kitchen sink, is NOT allowed in greywater reuse systems. Think for a minute about everything that might end up in a kitchen sink like animal blood, grease and larger pieces of vegetables. What if you just did an oil change on your car and you need to wash up? Having the kitchen sink drain to the septic helps keep potentially toxic water out of the greywater system and out of the biological filter that you are building in your greywater treatment plan.

Pro Tip

If you are happy to DIY then I highly recommend to buy this book by Art Ludwig, there is no better resource with regards to greywater technology. Create an Oasis with Greywater
Most of my designs are based entirely upon or modified slightly from the concepts in this book and Art’s decades of experience in greywater systems. For immediate satisfaction you can browse the site OasisDesign.net to dig deeper into the information.

First things to consider

The following are expectation checks for Terlingua greywater systems just to get you started before you start designing.

  • Designs are best before construction begins. A newly conceived outdoor shower or washroom is an excellent candidate for greywater reuse. An existing fully plumbed in-slab system that drains to septic is not.
  • If you leave your homestead for several months at a time, create a backup plan for the plants that depend on your greywater system. This could mean a neighbor using your clothes washer or a system designed only for annuals.
  • Our soil is salty and alkaline and greywater irrigation increases the salinity by the addition of pee, sweat and soaps (yes you do pee in the shower and almost all “natural” cleaners contain sodium laurel sulfate) Soil quality will degrade over time without periodic flushing of salts or replacement of all soil, only conceivable in a containerized bed.
  • Grewater is best if it infiltrates the soil immediately, holding onto greywater by draining into a holding tank or letting it pool at the surface is not good practice.

Should you grow food with greywater?

The chance of contamination from greywater goes up the less water is filtered and the closer it comes to your mouth. The best practice is to leave greywater for growing shade, not food. You should balace your risk tolerance on a scale of 1-10.
1 (least risk) = using greywater for sub surface watering of landscape plants
10 (most risk) = directly pouring greywater on lettuce plants and not washing the leaves before fixing a salad.
Somewhere in between is using greywater for an edible fruit tree such as a pomegranate– you must be the judge and I will make no claim that I told you either or.

garlic
Garlic grown with pure rainwater only

Conclusion

Data compiled by the EPA indicates that, as a national average, landscape irrigation is by far the largest single use of water at both residential and commercial sites, using 59% and 35% of water, respectively (EPA, 2013) In hot climates, outdoor use ranges from 59%-67% compared to 22-38% in cooler climates (AWWA, 1999). There is no doubt that water is our most precious resource so if we can use rainwater and use it twice then we can achieve a much greater efficiency in our landscapes. Using greywater to water roots, which then grows to provide shade to our living areas just makes perfect sense.