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Rainwater is What Your Plants Really Want

I could literally talk about water all day long. Where it comes from, how much we use, bottled vs tap, you name it, I usually have an opinion. When I see massive condo developments in downtown Toronto, my first thought is where are they getting all the water to support these residents? And subsequently, how are they dealing with the waste. My grandfather was a civil engineer so I guess I come by it naturally.


I'm not sure when this obsession started but I remember researching rainwater collection when we decided to build our cottage. It was 2003 and there wasn't much information out there that wasn't based in either Australia or Texas. Which makes sense. Necessity breeds innovation and areas affected by drought were motivated to come up with new and better ways to collect as much rainwater as possible. I had hoped to set up some system of collection off our roof at that time but I hit a few snags.


Our small-minded contractor didn't know how to help, meaning he had never set up a system before. Then I discovered the filter systems I wanted were based on Australian eavestroughs and weren't compatible with our systems. I admit I didn't force the issue at the time because water is not hard to come by here and it was just a seasonal cottage.


But now we live here full-time and my drive to collect water is back. Our garden has expanded and we need a lot of water to keep it going in the dry summer months. However, because we live in the country, we are not on any municipal water system. Our water has to be trucked to our house from a water depot in town and placed in our cistern. That makes it expensive.


Not only is there an environmental impact of gas emissions from the truck but also, our water prices are dependent on the price of gas. As a result, our water is almost 3 times as expensive as water supplied to houses through municipal pipes. I'm told the average person uses about 90 gallons (about 400 litres) a day. Toronto water costs about $0.016 a gallon or $1.44/day. In the country, we pay $0.045 a gallon or $4.05 a day per person. So in a year, a city dweller could spend $525 per person.


For us, if we used that much water, we would spend $1,478 per person. Due to the fact that we changed our toilets to dual flush and our taps and washers to low usage, we only use between 30 and 40 gallons a day for two people. But that number would increase substantially if we used town water for all our trees and vegetables. So you can see why we have decided to put the effort into rainwater collection.


If you are wondering, we are not right on Lake Erie so pumping water from the lake isn't an option for us. In addition, because Lake Erie is very shallow and has a tendency to produce a lot of algae. You have to use very long pipes to get deep enough for the cleanest water.


How to collect rainwater


Rainwater collection can be as simple or complex depending on what you are using the water for. For gardening, all you need is a bin and some eavestrough parts to get started. I would recommend filtering the water before it gets into the bin. This is because rainwater, as it pours off the roof, is not the cleanest stuff. On its journey across the shingles, it picks up all sorts of detritus (animal poop, leaves, pollen, sticks, asphalt bits). Filtering means you won't have to clean out a messy and moldy barrel in the fall. You also want to make sure your barrel has a lid as mosquitos breed in standing water.


Even though water is cheaper in the city, I encourage everyone to divert or collect rainwater. Drinking water has been treated to remove any harmful bacteria. Plants don't mind dirty water, they prefer it. At a minimum, you need to divert your eavestroughs away from the house. It is better to send this water into your lawn or garden as it relieves the pressure on the storm drains. If you want to collect it so you can use it to water your plants, there are all sorts of kits to get you started. There are lots of options, some fancy, some basic, to be found online or at your hardware store. For basic rain collection you will need:

  1. Rain barrel with screened opening on the lid.

  2. Downspout directed straight into the opening. You could add a seasonal diverter as well. See below.

  3. Overflow tap with a hose leading away from the house.

  4. Tap at bottom of the barrel for a watering can. Make sure the barrel is high enough off the ground to get the can under the tap. Some barrels come with stands or you can make something out of concrete blocks.

For our garden, we have a mixed bag of new and recycled barrels daisy-chained together to maximize collection. Luckily this is at the back of the house so I wasn't worried about what it looks like. As one barrel overflows, the next one fills up until finally, the last one overflows into the lawn. I'm hoping someday to clean this up into one cistern with a bigger capacity. With a small pump, we could use this water for the garden and washing the car if we wanted.


Right now I get my exercise filling watering cans and walking them all over the land. It's not pretty, but it gets the job done. The middle rain barrel fell victim to ice cracking so I had to purchase a rain barrel plastic liner to keep it going. We lost the lid along the way. Garbage cans make good cheap rain barrels. Just cut a hole in the lid, cover it with a screen, turn it upside down and place it back on the can. You might need to tie it down. Note the space for expansion.



Ultimately, my goal is to collect water for use in the house but this is a much more complex endeavor. There is much to be found online regarding this topic. Each country has its rules and recommendations but the end result meets the same requirements.


We just started this Spring so we are still sorting out the pipe connections, making sure they don't leak and that they can handle light and heavy flow of water. As we already have a below-ground concrete cistern that is connected to our household pipes, the idea is that as the above-ground tote fills up we will empty it into our household cistern.


We should be able to collect enough rainwater to use for most of the year. For a couple of months in the winter we would still have to get town water brought in.


To give you an idea of how much rain we could collect, the calculation is: roof square footage x amount of rain x 0.623). So 1" of rain off one side of our barn roof (approx. 525 sq ft) would equate to 327 gallons.


On average our location gets 35" of rain per year so we could potentially collect 11,447 gallons of water off a small roof. We consume around 14,000 gallons a year. As we add roof surface we can begin to collect more.


Collecting water for household use, even if you don't drink it, is a lot more complex. It requires first flush diversion systems before it gets to the cistern and then micro and UV filters before it gets to the in house pipes. We also need to replace our shingled roof with a metal roof to avoid all the asphalt debris. So this is a work in progress.


Half the battle was in setting up this system shown here. The diversion system was bought online but then many trips were made to the hardware store plumping section to get it all to fit together with our existing eavestrough.


For rainwater collection intended for household use you need:

  1. Metal roof is preferred - asphalt roofs shed too much debris.

  2. Gutter guards - to keep leaves and big debris from clogging your eavestrough.

  3. Seasonal diverter - because we live in a country with winter we need to be able to turn off the collection of water. Otherwise, water in the tanks can freeze and thaw, cracking the plastic. Winter mode sends any water down a regular downspout into the lawn.

  4. Basic filter - for large debris that get past the gutter guards. Can't have too many filters. No one wants to clean a cistern more than necessary.

  5. First Flush Diverter - this is considered essential according to the government recommendations. This diverter collects the first few gallons of water, rinsing off the roof of nasty bacteria resulting from animal poop, and sends it into the lawn.

  6. Final filter - for the really small stuff and to keep the mosquitos out of the tote.

  7. Cistern - rain barrels come in all shapes, sizes and price ranges. For our experiment, we chose a 275 gallon water tote. To prevent algae from growing, all barrels must be opaque. The tote we bought was white so we wrapped it in black plastic. Solves one problem but now we need a water level gauge as we can't see how much water is in the tank.

  8. Water overflow tap - in case you don't use the water before the tank fills up.

  9. Water level gauge

  10. In house water purification system - this includes a sediment filter and a UV filter. UV treatment is a non-chemical process that removes bacteria from the water. This is the most critical step in the process and usually the most expensive.

Here is the system explained. Still missing a few parts like the overflow tap and the water level gauge. Note the shingled roof. That will be replaced next year. I will write new posts as the system progresses.