Rainwater Harvesting in Dry Climates: Strategies for Success

Living off-grid in arid regions presents unique challenges, but also unique opportunities. One of the most crucial skills to master is efficient rainwater harvesting. While it might seem counterintuitive to rely on rain in a dry climate, strategic planning and the right techniques can significantly supplement your water needs, reducing your reliance on less sustainable sources.

The first key is maximizing collection. Don't just think about your roof. Consider every surface capable of channeling water. Gutters, of course, are essential, but consider extending them beyond the immediate house perimeter to collect runoff from sheds, patios, or even strategically placed tarps. The larger your collection area, the more water you'll gather, even during infrequent downpours.

Hack: A quick internet search will let you know the average rainfall by month in your area. Here is one website that you can use: https://www.usclimatedata.com/climate/united-states/us .

Your specific location can have a dramatic impact on the amount of rainfall that you can capture. In Washington State; Spokane gets 7 inches/year but Forks gets 140 inches/year!

Traditional above-ground tanks are common, but consider their limitations in hot climates. Consider burying at least a portion of your tank to keep the temparature lower during summer.

Material choice matters. Food-grade plastic is common, but can degrade faster in harsh sunlight. Consider more durable options like concrete or steel, though these require more upfront investment and careful sealing to prevent leaks and contamination. Regardless of your choice, regular cleaning and maintenance are needed.

Beyond storage, filtration is crucial. Even rainwater isn't perfectly pure. A simple first-stage filtration system, such as a mesh screen to remove larger debris, is a must. For further purification, consider a series of filters, progressing from coarse to fine. Sediment filters, charcoal filters, and even UV sterilization can provide increasingly higher levels of purity, depending on your needs and budget.

Tip: A "first flush" system will help keep dirt/dust/poop out of your collection system. Its easy to build and highly recommended.

Don't let the dry climate fool you; with the right approach, you can harness the power of the rain. Harvesting rain and putting it to good use on your property is very satisfying. Even if you only get very little rain, you can benefit from rainwater harvesting. Why not give it a try?

What size storage do you need to meet half your water needs from rainfall? What size storage do you need to meet all your water needs?

Here is a calculator (google sheet) that you are welcome to copy and use. It walks you through the steps needed with easy to fill in cells for calculating what size of roof catchment and what size of water storage you need to meet your specific water needs on your property. Check it out here: Rainwater Harvesting Calculator.