Category Archives: How-to

Rainwater Catchment System Key Factors

Rainwater Catchment System Key FactorsWhether you are designing your own rainwater catchment system or having one designed by a professional, success of your rainwater catchment system design is dependent on some key factors.


 

What do I want to accomplish with my design of a rainwater catchment system?

Irrigation, toilet and or laundry facility, supplementary to well water or city water, whole house usage, and sole source are the main purpose of designs.

How much rainwater can I collect from my roof? Will it be enough to supply my needs?

One inch of rainfall per 1,000 square feet of roof will yield approximately 623 gallons of water. Evaporation, wind, and spillage account for 15 – 20 % of loss. A 2,000 square foot roof with 36″ of annual rainfall may yield 44,856 gallons. With an efficiency of 85%, that equals 38,128 gallons.

One inch of rain is needed for the healthy growth of plants. This equates to .623 gallons per week for 1 square foot of planting, which can add up rather fast, so keeping your irrigation needs small and giving consideration to drought tolerant plants is recommended.

Toilet and laundry facilities account for 49% of household usage. Designing and building a system for this purpose alone can cut your water and sewer bill in half. New construction is the best time to implement this type of system however, retrofitting plumbing in an existing home can be accomplished.

Rainwater Catchment System Key FactorsIf the collection area is small or available space for storage is restricted, a supplementary system can be achieved with “slim line” style of cisterns or buried tanks. A small roof can still be effective in collection if used for a supplementary source to well water or city water.

Whole house usage, or potable water, can eliminate dependency on city water or well water, where you can still have city or well water as a back up during dry times. With the advanced filtration and UV disinfection offered today, safe, reliable drinking water for whole house usage will exceed the quality of most well and city water.

Now that you are considering what usage of collected rainfall would best suit your needs, we will discuss sizing, configuration, implementation, and maintenance of a designed rainwater catchment system in upcoming posts.

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How to Maintain a Rainwater Collection System

How to Maintain a Rainwater Collection SystemWhether your rainwater collection system consists of simple rain barrels or whole house potable usage, maintenance of your system is essential to its successful operation. Simple tasks will keep clean water flowing for years to come with little effort.

Here are tips for how to maintain a rainwater collection system:
  • Gutters should be kept free of leaves and pine needles so as not to create tannins or discoloration of the water.
  • If possible, cisterns should be placed in a shady area so as not to promote algae growth. A screen basket at the entrance of the cistern to keep debris from entering should be cleaned as needed.
  • If a sump tank is used for transferring water to cisterns, periodic cleaning will help keep the water in the cistern cleaner.
  • Any PVC pipe should be painted for UV protection and protected from freezing.
  • Filtration elements should be changed as needed with canisters cleaned at time of changing elements.
  • If the system is for potable use, the UV bulb should be changed per manufacturers recommendations.
  • Shocking the system with chlorine during UV change will help keep the plumbing lines disinfected.
  • Finally, keeping a log of maintenance will help keep a schedule of your tasks.

You can Click Here to download a free copy of RainBank’s recommended maintenance schedule.

How Do Bolted Rainwater Collection Tanks Hold Water?

Want to know how we hold water in rainwater harvesting tanks that are bolted together?

RainBank employees hang a 25 mil. PVC liner for an 18,000 gallon tank.
RainBank employees hang a 25 mil. PVC liner for an 18,000 gallon tank.

In order to hold water in rainwater collection tanks that are bolted together, first a heavy geo-textile pre-liner is hung against the steel wall panels to eliminate abrasions from the steel.

Then the liner is hung from the upper row of horizontal bolts.

Plumbing penetrations are made through the cement floor or through the steel walls with flanges.

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