CSA B805-18: The number that catches the rain

CSA Rainwater Harvesting Standards Cover

Rainwater harvesting has had a few roadblocks, but one of the largest was removed in May 2018.  In May, the Standards Council of Canada in conjunction with the Canadian Standards Association and  International Code Council, released the long awaited Rainwater Harvesting Systems National Standard, CSA B805-18/ICC 805-2018.

Why is this a big deal? Policy people have been waiting for direction, and building inspectors have been hesitant to approve as they have had a lack of information as to the important aspects of design.  This has lead many designers/installers developing their own procedure and format as to how they prepare a design.  The void in consistency complicates the task for those who assess and approve systems.  In short, without a standard, there is a lack of efficiency, and a degree of ambiguity for all.

The new standard is more robust than expected as it covers rainwater use for both potable and non-potable end uses for single family residences, multi-family residential and commercial.  Based on the water source and quality (risk factors) it sets out water treatment standards.  Ultimately all rainwater systems require a Water Safety Plan.

We jumped on this new standard as soon as it came out, and reformatted all our reports to match the presentation of the standard.   Now for every design we write a Water Safety Plan and do up a Design Plan, and submit these to the engineering firm we work with for review.  The engineer, when they are satisfied, stamps the Design plans and submits a Schedule B to the Building Department who is managing the permitting.

What are the weaknesses of the CSA B805-18 standard?  We are a little surprised that it allows asphalt shingles as a collection material for potable water collection.  We are also a little surprised that they do not recommend chlorination systems for single family residential applications as they are deemed “too complex”.  Though we rarely use chlorination systems, we think they are not complex at all, and as for asphalt, we ourselves will not likely take on a design job for such a collection surface.

Costs?  We have definitely increased our charge out with the addition of the Water Safety Plan to our regular Design plans.  The average single family residence will have to expect it to cost around $2500-$3000 of our design time for standard systems, and $2500 of engineer costs for reviewing and stamping.  That is on average $5500 outside of the costs of the actual system itself and the cost of permits.  Not small change.

 

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