, produced by the Texas Water Development Board (TWDB), costs range from a low of about 50 cents per gallon for large fiberglass tanks up to $4 per gallon for welded steel tanks. as tank sizes increase, unit costs per gallon of storage decreases.
The practice of using rainwater dates back to biblical times. It’s enjoying a revival in popularity today because of its quality and interest in reducing the consumption of treated water. Texas Hill Country residents will tell you water quality fluctuates greatly. High amounts of sulfur, calcium and iron are not uncommon.
"Trying to soften it or trying to condition the water just to the point where you can take a bath in it, let alone drink it, becomes pretty difficult. with rainwater you eliminate all those problems," says Barry Wall, owner of Rainwater Systems, inc.
Using the roof of a home, a network of gutters and PVC pipes, rainwater is funneled from the roof to a lined galvanized storage tank. for Wall, building these storage systems quickly went from a hobby to a fulltime job.
"It is gaining so fast that it’s hard to keep up with just the telephone calls to answer questions for people, whether they’re thinking about putting one in, or they’ve already contacted us and we’re working with them to put it in," he says.
Customers such as Collins have even discovered they use less soap and cleaning products around the house due to the purity of the rain- water. the TWDB states minerals in rainwater range from 2 to 20 parts per million (ppm) while municipal water is 100 to more than 800 ppm.
"It tastes good. It’s soft. We don’t have spots," says Stephanie Ertel, who with her husband started using a system a little over a year ago. "You can look at my sink; it doesn’t have those hard water spots. It’s just so much easier to live with."
People such as Collins and the Ertels build rainwater systems for a variety of reasons. sometimes those reasons overlap. for Collins, it came down to practicality and economics. for the Ertels, it came with a purpose.
The Ertels’ home stands alone when it comes to putting Earth’s gifts to use. their 2,000 square foot home is completely off the grid. not a single municipal utility is hooked up to their house.
Their home sits at the top of a hill on property that has been in Stephanie’s family for decades. It’s designed to absorb and repel heat when needed. Solar panels generate electricity and a state-of-the-art wood burning stove is fired up for all the cooking.
"We have a piece of property that was just begging to be off the grid and so that’s how we kept it," Ertel says.
The house has received several awards including the 2010 Energy Value Housing Award. it uses many natural and recycled materials. Cedar posts found on the property were cut for support, natural clay plaster lines the walls and counter tops are made out of recycled glass.
The million dollar question that comes with living off rainwater: Will enough rain fall to collect sufficient water to meet household needs? the short answer: yes.
The rule of thumb is 9,000 gallons of storage for every person in the home. the Ertels have a 20,000 gallon tank and use anywhere from 500 to 700 gallons a month. a rainwater collection system puts people in charge of their water supply. People in charge of their water supply tend to be frugal.
In 2008, the Kerrville area only received 13 inches of rainfall for the entire year. Even then, the Ertels never ran out. Approximately a little more than half of a gallon of water can be collected per square foot of collection surface per inch of rainfall.
"Our tank has been full for the last year and most of the time, when we see it raining, we see it overflowing and flowing down the hill," Ertel says. "Once you get it full, it’s easy to maintain the supply that you need."
During the drought, water in the nearby creek practically became unusable for Collins. she has a 16,000 gallon tank.
"I didn’t have the tank full in the summer when it was so bad here, and although I’m very frugal in my water use, I never ran out," she says.
The collection systems even withstood 9-degree temperatures last winter. the water inside the tank maintains a relatively warm temperature. the only real maintenance is changing filters every three to nine months and the UV light, which kills any potential pathogens, every year.
Rainwater harvesting makes more sense for rural residents, but Wall says a collection system on any scale makes sense to city people, too. he even takes it a step further with the opinion that rainwater collection systems are the present day answer to alleviate the state’s water worries. He’s not alone.
"I tell a lot of people, what’s happening here is we have an influx of people coming in. everybody is drilling water wells and what they’re really doing is just putting a new straw in an old Coca-Cola and they’re sucking the state dry," Wall says.
State and even local governments are rallying behind the idea of rainwater harvesting. the Texas Legislature passed laws in 2001 eliminating sales tax on rainwater collection equipment. in Austin, private customers may receive a rebate of up to $500 on the cost of installing a preapproved rainwater harvesting system, while commercial entities may be eligible for as much as a $40,000 rebate.
It’s clear that for some, the investment in such systems has far exceeded expectations.
"You wash your hair and it’s soft. it smells good. it tastes wonderful," Collins says. "I’ve gotten to where now, when I go visit friends and family, I take my drinking water with me. Because no matter what kind of water they have, it just doesn’t taste as good."
Harvesting the Heavens
ok i need some answers to my home work 
Why do cats never drink the water intended for them?