City Water Hook Up? No Thanks!
The multi-faceted rainwater and greywater system that Ecovie just implemented is just too cool to cover with only the usual project summary sheet! Here’s the story! Our clients in Atlanta just moved in to their newly built home in the Grant Park neighborhood. Because the lot they chose had no city water (or sewer) connection, they would have had to pay a lot to have them installed. Because the lot was high on a hill and other factors, the cost of running these lines turned out to be way more than expected. So, logically, they went a different route.
They installed a rainwater collection system as their fresh water supply and an Aqualoop greywater recycling system to minimize fresh water demand. Even though their new dream home is in the heart of Atlanta, their water system is totally off the grid, with no city water connection at all!
The system is designed to easily meet all water needs for the Fosse’s both indoors and outdoors. The of 4 plan to have an extensive apple orchard and vegetable garden, so we’ve designed the system for comfortable living through great water management. Some highlights of of this off grid system:
- Assures water supply for an average of 5 inhabitants for all indoor use as well as for orchard and garden watering.
- Assures on site stormwater infiltration.
- Provides clean, treated rainwater that exceeds both Atlanta City water quality and EPA drinking water standards.
- Provides treated greywater that meets NSF 350 commercial standards which means the treated water can be stored for extended periods and used for spray irrigation.
Let’s go through the details!
By the Numbers — Water Supply:
- The Fosse’s will be using around 20-25 gallons per day per person of fresh water indoors (i.e. clean, pristine rainwater). That is less than half the amount an average person uses. They achieve this through Aqualoop greywater recycling and low flow fixtures.
- Aqualoop recycles around 80 to 115 gallons per day depending mainly on how long their showers are!
- Their 1.75 GPM Hansgroe shower head puts out great flow, unlike some others with their piddly flows.
- The Fosse’s have budgeted their showers at 5-8 minutes long. Longer showers mean more water for plants but more rainwater usage.
- With 5 minute showers and low flow heads, the Fosse’s expect to generate only 17 gallons of greywater per day per person, far below our typical estimate of 33 GPD/person.
- This adds up to around 35,000 gallons of rainwater needed per year for indoor use. Check your own water bill and you will see how low this usage is!
2. From the 2,400 square foot rooftop, around 75,000 gallons of rain hit the roof each year on average with around 50″ of rain a year in Atlanta. Of this amount, some water evaporates or overflows the tanks to the rain gardens, so around 53,000 gallons on average is actually used. In a drought year like Atlanta had in 2007, the amount drops to around 43,000 gallons which means less rainwater is available for outdoor watering but still enough for what is planned for gardens and landscaping.
3. In a normal rainfall year around 18,000 gallons of rainwater is available for outdoor watering. During drought, this would be cut back to around 8,000 gallons of rainwater. Typically, the only rainwater that is used is water which overflows the main rainwater tank into a special tank for outdoor watering. This tank also holds any leftover treated greywater.
4. Greywater captured from showers, laundry and bathroom sinks averages around 85 gallons a day from 5 people and can supply around 27,000 gallons of treated non-potable water. Around 13,000 gallons is used in toilets and the cold water portion of laundry, both of which are very low-flow fixtures (1 gpf for the toilets and 15 gpl for laundry). This leaves 14,000 gallons for use outdoors.
5. So, during an average rainfall year, there should be over 32,000 gallons for outdoor watering which works out to 615 gallons a week year around. During a drought such as the one in 2007, there may only be around 430 gallons available a week much of it treated, recycled water. With this analysis, there should be more than enough water even during drought conditions! But, please keep in mind that during the worst drought in the last 60 years, Atlanta still had 32 inches of rain! California would love that amount of rain! 32″ of rain would be a super El Nino year!
Design Details — Water Geek Zone:
Here it is in a nutshell:
- 6,000 gallons above ground HDPE tank rainwater storage (2 x 3,000 gallons) for the 2,400 square foot roof. That means it takes around 4.2″ of rain to fill the tanks.
- Ecovie installed a rainwater system which follows the City of Atlanta code for potable rainwater. Yes, there is a special ordinance there for potable rainwater!
- Standard capture best practices with PURAIN prefilter, first flush, calming inlet, and floating intake.
- Treatment using manual backwashing sediment filters, UV, and carbon block filtration. This has been Ecovie’s standard potable rainwater design and it meets the Atlanta ordinance. However, another option would have been to use Aqualoop for rainwater, although that is not yet covered in the ordinance..
- The rainwater tank has an electronic level gauge, the Rainmaster RMD-24.
- Aqualoop MBR greywater recycling technology with single membrane cartridge for 80-120 GPD treatment capacity in a 180 gallon bio-reactor and 300 gallon treated water tank.
- Greywater is pumped by a Rainmaster ECO 10 system which is ultra energy efficient and works great for toilet tank re-charge, laundry, and hose irrigation.
- The rainwater tank overflows to a 2,500 gallon Excess Tank. Excess greywater is also stored here. If you think that mixing greywater with rainwater is heresy, consider this:
- Aqualoop treated greywater has less than 2 CFU e. coli and <5 BOD. That means it is comparable in quality to rainwater on these measures and according to NSF 350 standards is just fine for spray irrigation and extended storage.
- Rainwater is obviously fine for irrigation too.
- Mixing the two is just fine for irrigation, which is what the plan is.
- This plan is permitted and approved by the City of Atlanta.
- The Excess Tank overflows to a rain garden, so all stormwater is kept on site. By the way, all wastewater is kept on site too….
Here is more detail:
- The rainwater and greywater process flow schematic:
2. The Aqualoop greywater treatment process is classified as an MBR process (membrane bioreactor). An aeration step biologically treats incoming greywater which has around 100-180 PPM BOD and 100 to 1000 CFU/100ml e.coli. Aqualoop treated greywater is clearly more similar to captured rainwater or even potable water than it is to raw greywater. Other greywater “treatment” processes with simple bag filters and even with chlorine addition tend not to come close to these standards. Water treated to in this way should not be mixed with rainwater and should be used within 24 hours to prevent biological progression to blackwater. For typical sizing, click here.
These photos show the Fosse Aqualoop system in action.
Also, please check out our detailed Aqualoop design information here.
This example of an off grid water system is certainly made easier by being located in the rainy southeast US. Atlanta in fact tends to have relatively constant rain through the year with no dry and wet season. The Fosse’s system shows how water can be managed to comfortably meet all a household’s water needs using far less fresh water regardless of location. Imagine putting a system like this is drier regions. The Aqualoop system will have the same effect everywhere with a 40% fresh water reduction on average. Rainwater can be used when available to further reduce municipal and well water demand. So, one can easily envision a 60% to 100% reduction in municipal and well water demand for residential use, be it in single family homes or in large high rises or hotels. This type of water management would go a long way to reduce the burden growth (both economic and population) puts on traditional water supplies.
As always, I encourage you to consider taking some or all of these steps for your upcoming construction projects, both large and small. At Ecovie, we are solving the world’s water challenges one building at a time!