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After the first part of our four-part Rainwater Harvesting webinar series, Rainwater Harvesting as a Runoff Reduction Tool, participants had the opportunity to ask our Rainwater Harvesting experts questions.

We didn't have enough time in the hour to answer all of the questions, so we are posting them here so that they are available to all.

These were the top 3 questions asked about Rainwater Harvesting Cost:

  1. Q: Are there cost estimates available showing the cost of the cisterns, treatment, pumps, etc?
    A: Each project is unique, and there is a wide range of features you can include in a design, so charts would not be accurate in most cases. A rough guide for a commercial scale system capturing an acre of impervious area would be:

    •   Pretreatment: $5,000 to $15,000
    •   Cistern: $20,000 to $40,000 (cisterns often end up sized similar to a Water Quality Volume)
    •   Mechanical System: $5,000 to $40,000 (this varies widely depending on flow rate and treatment)

    For larger projects, the cistern would scale up, but the pretreatment and mechanical systems may not need to be larger.
  2. Q: How long it will take to pay off a RWH system?
    A: ROI is very dependent on sizing and what factors are included in the savings. Over a 20-year life, many systems can surpass breakeven and provide a modest ROI based only on the initial capital cost, future maintenance cost and future water utility savings. Many do not, however, and it can be difficult to justify a system solely on water utility savings.

    However, no other stormwater practice can compare to rainwater harvesting because it is the only one that provides a hard dollar value for the volume of water retained onsite. On dense or urban sites, the rainwater harvesting system can reduce or eliminate the ned for a bioretention system, which provides a developer more space for value added amenities. In many cases, this can quickly provide very healthy ROI for a rainwater harvesting system.
  3. Q: How do utilities bill for wastewater generated by fixtures supplied by non-potable sources?
    A: They can require a sewer meter to be installed or they may request a water meter coming out of the cistern. We installed a RWH system at one of our manufacturing facilities where we use a lot of wash water.

    We placed a water meter on both the cistern and the make-up water line. The utility can read the meters to determine sewer volume. As RWH become more widespread, we expect utilities will figure out how to be paid for the wastewater treatment services they provide, which is only fair.

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