Megan Navarro
HAYS COUNTY — As groundwater resources have started to decline across Central Texas, many landowners and residents are starting to look elsewhere to supply their homes and systems.
Rainwater harvesting is the practice of collecting, storing and using rain that falls on rooftops or other surfaces, which can then be used for irrigation, livestock and household uses — including consumption — when properly filtered and disinfected, according to the Hill Country Alliance, a nonprofit that works across 17 counties in the region to protect the land, night skies, character and water.
Due to more frequent droughts, increased population growth and a stress on limited groundwater supply, alternatives like rainwater harvesting have become a more viable option for many people.
“We are seeing groundwater decline across the region and so, as we think about what a resilient water feature looks like in Central Texas, it does mean diversifying our supplies, so that we're not just relying on groundwater. We've seen rainwater harvesting to be a reliable alternative when systems are designed correctly,” said Marisa Bruno, water program manager for the Hill Country Alliance.
There was a large rainfall in Central Texas last July that filled up the Highland Lakes, which was beneficial for the city of Austin, but groundwater levels within the Barton Springs Edwards Aquifer Conservation District (BSEACD) jurisdiction still remained low, explained Shay Hlavaty, communications and outreach manager for the district. Now, the district is approaching — though it has not officially declared — Stage 4 drought, which has never been reached before.
“A lot of folks in our territory rely 100% on groundwater, along with at least 50% of Texans. Rainwater is a really great alternative, either to rely on it fully or to supplement people's well because whenever that rain falls, you catch like almost 100% of it,” Hlavaty said. “But with groundwater, when it rains, only a fraction of that amount of rain actually ends up in the aquifer, 5-10% of it. Even if it's going into those lakes and creeks and rivers, like those reservoirs and everything, there's a lot of evaporation happening out of those, too. So, by catching it directly, you can use it immediately.”
Bruno and Hlavaty both continued to emphasize the value of rainwater harvesting, which includes the following: the quality can often be better that what is found from groundwater; homeowners have more control of their system when needing to do maintenance and cleaning; and it can be less expensive than drilling a new or deeper well when supplies run low.
A 2025 study conducted by The Meadows Center for Water and the Environment at Texas State University found that rainwater harvesting can be used as a fully reliable water supply option in the state, even during severe drought periods. The study showed that a 3,000-square-foot roof with 30,000 gallons of storage can meet indoor household water needs statewide, as well as widespread rainwater harvesting would not reduce levels in rivers and aquifers — it would be less than a 1% reduction in runoff and recharge.
“What that report shows is that if you do have the sort of roof space or capture space size correctly and you have your storage space size correctly, you can survive even the drought of record. Even in a year with below average rainfall, with the system dry and designed correctly, you should have no issues getting through the year with that supply,” Bruno noted. “I think there's this myth around rainwater harvesting that because you're dependent on rainfall, it's not reliable, but we know it's going to rain. It might rain less in some years than in others, but it does always rain.”
There are some regulations on rainwater harvesting, depending on the specific system that is being used, said Bruno. She added that if someone is designing a rainwater harvesting system for their own personal use, there is limited regulation, but there could be more for commercial use.
Learn more about rainwater harvesting and specific systems at the following links:
• Hill Country Alliance: bit.ly/4sSonQA
• Barton Springs Edwards Aquifer Conservation District: www.bseacd.org/rainwater-harvesting
