If you’re not familiar with the term “graywater,” it refers to water that has been used once for showers or laundry and can be used again for filling toilets, (and sometimes watering lawns as well). Some systems will also take water from sump pumps that can be pumped into a recovery tank. The point about reusing water is that it prevents the use of “potable” (treated, drinking) water for being used for things like flushing toilets. In an average family household, the largest water consumption activities are:
- Showers and baths: 35%
- Toilet flushing: 30%
- Laundry: 20%
- Kitchen and drinking: 10%
- Cleaning: 5%
Many of the municipalities around the Greater Toronto Area are looking to reduce water consumption. As more people move into the GTA, more pressure is put on our water system. If we can reduce water use we can delay infrastructure upgrades, save energy costs (water treatment costs), and most importantly, conserve fresh water use.
Enter the graywater system. A graywater system can conserve 35-40% of your water consumption by taking all water used from showers and baths and direct it to fill you toilet bowls, thereby displacing 30% of your total household water consumption. In fact, at current water rates, Chris Thompson of Greyter Water Systems, estimates that a homeowner would save 30-40% on their water bill annually with a graywater system.
After going through a second use in toilets, the water is then flushed into the main sewage system.
In addition to the advantages already mentioned, there are a few others as well::
- It is not dependent on rainwater.
- It can be used with low-flow toilets and showers.
- It means that potable (treated, drinking) water is not used for flushing toilets.
- It eases the burden on the city sewage treatment system.
The main drawbacks of a greywater system:
- Retrofitting an already built home is difficult unless a renovation is being undertaken.
- The tank requires a certain amount of space in your basement.
I contacted Chris to ask him a few questions about a graywater system:
[Chris Thompson] Systems start at $2190 for a modest sized home with a typical family. Installation varies depending on the home. For new construction or renovations where there is already some plumbing work being done or simple retrofits where the plumbing is exposed or easy to get to, the installation cost ranges from $300-$800 including materials. This would include all of the rough in materials (pipes), valves and fittings and labour required.
[Chris Thompson] I or one of my dealers would provide support to the plumber who would do the rough in and make the system connections. This is mainly a plumbing job and it must be done to comply with Ontario Building Code. Most plumbers need only a little bit of guidance from us to be able to do the installation. The dealer can also provide start-up and an orientation for the homeowner if required.
[Chris Thompson] Brac is currently the only approved residential system in Ontario and yes, I am building the dealer network for the province now.
[Chris Thompson] That would be the simplest of all installations.
[Chris Thompson] With a Brac System, there is no need to upgrade beyond 6l toilets as all of the water will be reclaimed and 6L toilets will become 0L toilets. Having said that, dual flush or low flush toilets will increase the capacity of the system. ie. The RGW150 is ideal for a family of 4. With dual flush toilets, it would be more capable of handling 6 occupants.
Most of the good low flow shower heads restrict water to about 7 litres per minute (much less and people tend to shower longer and don’t get a comfortable shower). With an average shower length of 10 minutes, 70L of greywater would be reclaimed. On average, we flush 7 times per day per person or 42L with 6L toilets. This means there will usually be a surplus, even with low flow shower heads.
Because there is a surplus, we typically do not connect the laundry because we already have enough water. In some installations, it is difficult to get to all of the showers and we might tie in the laundry to supplement. The impact is that lint will need to be cleaned from the filter more often and colour will get through the filter.
We never collect from kitchen sources due to the organics and oils that are present.
[Chris Thompson] Guelph is the first. They are just finishing up a pilot rebate that was to cover the first 30 systems installed in new construction through selected builders. They are in the process now of implementing a permanent rebate of $1000 for anybody who wants to install a system. When all of this becomes final, I will be approaching other municipalities with the details.
(Note: featured image is courtesy of the city of Guelph, Ontario)