With more than 30 years’ experience in the residential and commercial water treatment space, Mark Nelson is a Class 1 Drinking-Water Operator and a CBWA (Canadian Bottled Water Association) Certified Plant Operator. As founder and president of Nelson Water in Ottawa, Mark focuses on dealing with challenging water treatment system designs for problem water. He also heads the largest water bottling plant in the city of Ottawa with a delivery network throughout the Valley.
Many people rely on rainwater as their primary water source if they reside in arid regions. But, this is an attractive option for other people with more reliable sources of water to supplement their supplies. Rainwater harvesting has gained significant traction in recent years and this is an interesting topic to explore. In this article, we will take a closer look at rainwater harvesting to help you decide if it’s a good fit for your home and how to do it safely.
Rainwater Harvesting Basics
When we harvest rainwater, we’re collecting the rain and storing it for later use, including bathing, irrigation, and even drinking. The rainfall is collected from the run-off that occurs on a structure and this is usually some type of roof. The water is directed to a storage tank or directed to the groundwater to replenish those water sources. When rain falls on a roof, it’s collected in the gutters, directed to a downspout, and then into the storage vessel. There are various rainwater harvesting systems to explore and they vary a great deal in terms of complexity, capacity, and efficiency. A simple home system may be a water storage barrel under a downspout that you can use to water your plants. But, there are more complex options with large cisterns that can supply a cooling tower in an industrial plant. When rainwater is harvested correctly, it can be safely used for drinking and cooking purposes.
3 Types of Rainwater Harvesting Systems
There are three basic rainwater harvesting system types. They are:
1. Rain Barrels
As we mentioned earlier, this is the most basic, common, and easiest way to get started with rainwater harvesting. A rain barrel is placed under a downspout and the rain is collected from the roof. The most common rain barrels have a capacity of 50 gallons with a spigot at the base where you can draw the water. Some rain barrels allow you to attach a hose or link the barrel to an irrigation system.
2. Dry Systems
A dry rainwater harvesting system works on the same principle as a rain barrel but the storage volume capacity is much higher. The larger storage tank is placed in a convenient place on the property and pipes from one or more gutters are directed to it. So, when the rain falls the tank is filled quickly and it’s ready for use later. This type of system is referred to as “dry” because the pipes are fully dry between bouts of rainfall. The connected pipes are fully emptied into the storage tanks due to gravity.
3. Wet Systems
A wet rainwater harvesting system is very different from a rain barrel or dry system. The pipes are located underground and during rainfall, the water will flow from the gutters to these pipes. Then the water will rise inside a vertical pipe to fill a surface or underground water storage tank. These pipes are constantly filled with water and this is why this is referred to as a “wet” system. The pipes never dry out, this means that a wet system is vulnerable to bad water phenomena, including stagnation, anaerobic fermentation, and mosquito infestations. These risks can be mitigated with the installation of screens and regular water draining. Although a wet rainwater harvesting system requires more maintenance, they are an attractive option for many people. Because the storage tank can be located further from the home and the pipes are underground, this is a tidy and more aesthetically pleasing system.
Is a Demand Pump Required?
If you want to use harvested rainwater in your home, you will need a demand pump. The most reliable option is a water booster pump that is a flow-based system that matches the demand. An alternative option is to use gravity, but this only works if the water tank is located at a higher elevation than your home.
Is Harvested Rainwater Safe to Drink?
Rainwater should be safe to drink because it has been naturally distilled in the atmosphere before it falls as rain. But, in reality, this is not the case because there are airborne and surface contaminants that will degrade the water quality. Harvested rainwater should not be used for drinking and cooking purposes with some filtration and/or water treatment. Bear in mind that most roof structures are covered with dust, dirt, bird poop, and other contaminants that are added to the water during runoff.
What is the Best Water Filtration System?
If you want to make your harvested rainwater safe for consumption, it’s important to remove the bacteria and other contaminants that can harm your health. At the water treatment plant, a series of filters and the addition of chlorine based disinfectants are used. Adding a final level of protection in your home to remove contaminants from public water, private well water, and harvested rainwater is advisable. There are many types of water filtration systems and their efficacy will vary depending on the makeup of your water supply. But, one of the best filtration systems for home use is reverse osmosis or RO.
What is Reverse Osmosis?
Reverse osmosis (RO) is a mechanical filtration system, no chemicals are used and the water is purified to a very high standard. At the heart of the RO system is a semi-permeable membrane with tiny pores. The incoming water is forced through the membrane filter under pressure and the contaminants are left behind on the surface. Periodic flushing rinses these contaminants into the drain to ensure that the RO system is efficient. This process takes time, the filtered water is collected in a storage tank and it’s accessed with a dedicated tap. The most common RO filter is a point-of-use system installed at the kitchen sink for convenience. The water at that tap is very clean for drinking, cooking, making high quality ice cubes, and more. A whole-house RO system is far more complex, but this delivers cleaner water to every tap, appliance, and plumbing fixture.
If you need help setting up your rainwater harvesting system or you want to install a RO filtration system, contact your local water treatment specialist.