We believe strongly that water conservation is much more critical than most people recognize and water conservation will become equally as important as energy conservation.
To help reduce our water demands, we will use low volume plumbing fixtures and drought tolerant, native California species in our landscaping. Importantly, we will have an underground cistern that will capture 100% of the rainwater that falls on our roof.
Under the LEED-H guidelines, Water Efficient (WE) has three components: Water Reuse (WE 1); Irrigation System (WE 2); and Indoor Water Use (WE 3). At this point in our project, we need to ensure that the physical properties of our site will support our design (i.e., not constrain the elements in the design) so a cistern is critical. The use of a cistern is covered under Water Reuse.
Water Reuse includes WE 1.1 Rainwater Harvesting System; and/or WE 1.2 Graywater Reuse System; or WE 1.3 Use of Municipal Recycled Water System. There is a maximum of 5 points available in Water Reuse and up to 4 of those 5 points can be in WE 1.1 Rainwater Harvesting System.
We do not have a Municipal Recycled Water System and will not be utilizing a Graywater Reuse System; consequently, we need to focus on a Rainwater Harvesting System.
The design of our Rainwater Harvesting System will include 100% of our roof area and the cistern must be sized to hold all of the water from a 1-inch rainfall event. Given our roof is 63’4″ by 63’3″ (almost a perfect squate), we have 4,006 sq ft of roof area. For a 1-inch rainfall event, our roof will capture approximately 2,484 gallons of rainwater.
Our property cannot support an above-ground cistern so we need to have a location for an underground cistern. The swimming pool and existing trees at the back of the house limit our location to the front yard. It would be great to have a cistern under our driveway but that would come at a significant cost.
Alternatively, we have some space at the East side of our front yard where we removed a Canary Island Pine tree. Removing the stump will require an excavation, so it will make a feasible location for an underground cistern. We will use the excavated soil to fill the remaining voids at the front of our house.
Our civil engineering team, from Bowman & Williams, were reviewing our alternatives and Casey Carlson recommended that we consider the CUDO System. He was familiar with the CUDO System and though it could be integrated with our site easily. We liked Casey’s design and recommendations.
The CUDO System is an innovative product that include 2×2 ft plastic cubes, which can be configured in a number of ways. A bladder goes around the internal plastic cubes, creating the cistern. The CUDO System could include a pump that can be connected to our irrigation system, thus reducing our water demands.
Given our space availability, Bownman & Williams recommended that we put in a CUDO System that is 4 cubes wide (8 ft) by 8 cubes long (16 ft) and 2 cubes deep, that is just over 24 inches below grade. The underground cistern will have a capacity of 492 cubic ft, or 3,677 gallons. This will allow our cistern to hold approximately 1.5 inches of rain. Once the cistern is full, it will have three pipes to carry the overflow, via gravity, to our storm sewer.
The team from CUDO Stormwater Products, Inc. included Doug Allard, Ron Powers, Jon McDonald and Sue Lillo. They tailored the design from Bowman & Williams and helped to establish the detailed specifications.
Site Visit by Sue Lillo
The sales representative for Northern California, Sue Lillo, was going to be in the area so we invited her to visit our site. Bryan hosted her site visit and showed Sue the various features of the house.
Sue confirmed that the location would work and that she would ensure the product was available and delivered when we need it.