1. Why harvest rainwater?

Rainwater can be an economical alternative to public water in many instances, especially for exterior water uses such as irrigation, filling water features and outdoor cleaning. While indoor uses are approved in other areas of the country, the St. Louis City and County plumbing codes allow indoor use only for toilet flushing. Potable water in our city and county is very plentiful and of very high quality. However, increasing infrastructure maintenance costs resulting in higher rates are inevitable.

Rainwater can supplement limited ground water resources. Well water extraction rates are reducing and the quality of many wells is falling below safe requirements. In arid regions, rainwater may be the only viable source of water available. For those who wish to be completely independent or “off the grid”, rainwater harvesting offers the only solution independent of all utilities.

Storm water mitigation issues are of constant concern, especially in the “hilly” Midwest. Regulations are getting tougher and the cost of building new and maintaining existing storm water facilities is ever increasing. As regulation moves toward individual owner responsibility, rain water harvesting brings the simplest and cost effective method of storm water management. 

2. What is the quality of harvested rain water?

Rain water is the “purest” form of water provided by nature. Its quality can be affected by a number of variables that tend to be site or region specific. The water itself is very low in minerals, low in Ph and has no added chemicals such as chlorine. The low mineral content makes it ideal for laundry, dish washing, hair and car washing. Lacking chlorine and other additives found in potable water, it is superior for plant watering, general irrigation and fish pond filling. Sanitization methods are simple and easily administered when and where necessary.

There are a number of other factors that will affect the quality of rain water once it reaches the roof or catchment surface. The atmosphere can add impurities but most contamination comes from the catchment surface and conveyance components. See our design page for a discussion of roof surfaces, conveyance components and inlet filtration recommendations. 

3. What are the uses for harvested rain water?

Currently the primary use for harvested rain water is landscape irrigation. Other exterior uses include filling swimming pools, washing cars or outdoor furniture and structures. In most other countries and some parts of the United States, rain water is used indoors for toilet flush, dish washing, bathing and other non-potable uses. Some cities and counties in the U. S. also allow potable uses once specific sanitization requirements are met. In much of the rest of the world it is common to use harvested rain water for all needs. Specifically, in St. Louis County, the only approved indoor use at this time is toilet flushing. Some surrounding counties either do not have regulations or allow for expanded use of rain water. Check with your local code authorities for guidance. 

5. How much water can I harvest?

The answer to this question is dependent on a number of variables. Included are the size of your catchment surface; the annual rainfall amount and regularity for your area; and the efficiency of your rain water harvesting system. Briefly, a good rule of thumb for water capture is one-half gallon of water for every square foot of catchment surface per one-inch of rainfall.

Example: 1″ of rain on a 2,000 square foot roof: 1(.5) x 2,000 = 1,000 gallons.

The total captured water for any location over a period of time is dependent on the actual rainfall experienced during the period. Rainfall regularity will also play a part in determining the most efficient and effective storage capacity for a specific site. 

6. Can I design and install my own rain water harvesting system?

Simple systems for landscape watering can be successfully designed by non-professionals. By following some of the simple rules available on this website you may be able to put together a simple system. You can request one of our “Rainwater Handbook” publications and use the information to help design small systems.

Large systems and especially those with the potential for significant water flow should be designed by a professional. Water is very heavy and moving water can be very dangerous. The engineering demands of large scale systems (whole house or commercial) reach into the areas of structural considerations, safe water flow dynamics, proper component selection, construction practices, excavation practices, etc. Please consult with our design professionals before attempting a large scale system design.

Installation will tend to follow the same guidelines as the design discussion. Small, simple systems can easily be installed by someone with minimal mechanical understanding and simple hand tools. Larger systems usually require specialized tools and mechanical knowledge. Professional training is required for many of the disciplines necessary for large system installation. Rainwater Harvesting Supply Company can provide names of qualified installers depending on the design and installation parameters. 

7. What are the long term maintenance implications?

Rain water harvesting system maintenance will vary with system design and complexity. All systems require regular inlet filter cleaning. These intervals will be learned over time as individual sites have differing elements that add to filter debris. Small systems usually require the removal of the tank or barrel during the winter season where the temperatures fall below freezing. This may not require much more than draining and storing the rain barrel. Larger above ground systems will have more complex winterization procedures. Beyond winterization and spring “start-up”, occasional cleaning of the barrel or tank may be necessary during the capture season.

In-ground systems are usually placed below frost levels and typically will not require any special effort for winterization. As long as filters remain clean and the overflow remains unobstructed, little maintenance is required. One should always keep constant observance of water quality.

If the system is complex and incorporates pumps, float switches or a control system, these should be monitored and tested periodically. This is usually done by a professional, but site specific maintenance instructions allow for owner monitoring.

Most rain water harvesting components are built very well and should provide many years of trouble free operation if properly installed. This applies even in complex pump and control system featured systems. Maintenance costs are typically insignificant in comparison to the advantages of rain water harvesting. 

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