Raindrops keep falling on my roof
By Bob "Hot rod" Rohr
Radiant Expert
Being well versed in the piping trade, I've decided to try and wrangle some of those drops. Rainwater collection systems are getting a lot of attention again. I remember a lot of homes with cisterns in the basement as I grew up in the western New York area in the '60s. I remember those systems being used mostly for irrigation, specifically for lawn sprinkling.
These days I see more complete rainwater systems being offered. Factory-built systems with various levels of filtration are available. The basic system might have a filter at the roof or downspout for leaves and debris. Some systems have clever valves, or collection tubes, which cause the first small batch of water to be dumped. This allows the roof to be rinsed, so to speak - to wash the roof of any bird droppings, etc. before flowing into the tank. Good thinking!
Additional filters can be added at the inlet into the storage tank. Filtration as simple and basic as spin-on cartridges can be installed or as high tech as a RO, UV and carbon filters. Chlorine can be added for disinfecting, and the taste and odor can be removed via carbon block filter before going into the home. It is quite possible to turn rainwater into safe potable water, if desired. When you think about it, with enough technology, even sewage can be turned into potable water.
My plan for my own home is to use the rainwater for toilet flushing and, possibly, laundry use. We have a great producing well for our domestic water in terms of gpm, but the water is very hard and has high iron content. It takes a multi-stage, water-wasting filtration system to make it user friendly. With the rainwater component, I hope to cut back on both water softener and rust filtration use.
The HDPE tank I purchased is not listed for potable water storage. I bought an underground style tank with a 1000-gallon capacity. The tank has two large manhole sized openings on the top. I piped some PVC lines into the tank for extracting the water and for wiring to add a level sensing system to cut the pump out as the level drops. I'm still trying to decide between a submersible and a variable speed well pump, mounted above the tank. I like the idea of the new variable speed, ECM well pumps that work efficiently and without a large storage well tank.
Another option would be a PV powered pump. It would fit into my "green" theme. But I am considering the cost of a high gpm DC pump with batteries. Is the juice worth the price? I like my green lean. I'm thinking about the Viega Manabloc system for my distribution, with the rainwater piping well labeled. I noticed that a purple-colored PEX is used in Europe to denote rain and graywater piping. Some green PEX would be a nice match for rain or graywater systems. I did see some sample green PEX manufactured from recycled PE. What a nice touch, to build a green pipe for green technologies.
Controls are another area I am still "noodling." Certainly, a seamless switch to well water, should the rainwater tank run low, would be ideal, as the tank may run low and lock out when I am out of town, like the boiler does. Manual rainwater operation may not be what my wife wants on her to-do list.
My system is pretty much home-built, with common off the shelf components. All of the parts and installation are well within the comfort level of readers here. My largest expenditure so far was the rental on a small mini-excavator for digging the hole for the tank and piping runs to the tank.
I also decided to build a small greenhouse over the top of the tank. I hope to heat this 60 square feet of slab on grade with solar and water the crops with collected rainwater. I installed a PEX loop below the under-slab insulation for a dump zone for the solar, if needed. It would also act to preheat the earth below the well-insulated slab. A PEX loop is also included in the greenhouse slab for cold weather tempering of the space.
The next step will be a separate HW tank, solar powered, of course, to heat the collected rainwater for laundry use.
I have noticed some factory-built systems showing up on the market. Texas seems to be a leading state when it comes to rainwater collection technology and components. Here is a link to a rainy day site, should this technology grab your attention -- www.harvesth2o.com.
On a recent trip to St Croix, I found that rainwater is a crucial part of life in the islands. Desalination is slow and expensive; rainwater is a simple solution. But I am hearing that rainwater collection may be banned in some areas. Should you decide to let some raindrops slide down the pipes to your system, check into the codes and laws in your area first.