Rainwater Harvesting Services
The Rainwater Harvesting Process
What we do is try and capture as much rainwater that falls onto your roof and then use the rain water for:
- Toilet flushing
- Washing machines
- Garden irrigation systems
- Car washing
- Swimming pool and pond top up
Traditionally, rainwater is used to water the garden. This may be a simple set-up where rain is caught in a rain barrel (butt) or small rain tank (JoJo tank or similar) and a watering can or gravity is used to water the garden around you. Larger set-ups allow capture of rain water from large areas of the roof, piped to a single large tank or tanks, and a pressure booster pump supplies the water to tap points or an irrigation system.
Rainwater can also quite easily be suitable for all non-potable water uses. This helps to replace around 50% of municipal water. In an existing house, if plumbing permits it, rain water is used for toilet flushing, washing machine and dishwasher use. This may also be a great option for you to explore if you are building a new house and want to integrate rainwater harvesting into your house. Because you are replacing more municipal water with rainwater, your payback period is shorter.
With additional filtration, you can replace all potable and non-potable water sources within your house. This a normally the most viable option for people who want to use the rainwater inside the house on a home that is already built. Unfortunately, retrofitting a rainharvesting system into an older house and trying to split the water feeds between potable and non-potable sources can often not easily be financially or practically accomplished. It is then better to replace all municipal sources with rainwater sources. A simple manual or automated switchover valve allows you to easily switch back over to municipal water if the rainwater is finished or if there is a power failure.
Source: Water – How is it used at home, HE Jacobs, LC Geustyn and BF Loubser, 2005
Source: Water – How is it used at home, HE Jacobs, LC Geustyn and BF Loubser, 2005
How Rainharvesting works
The rainwater harvesting process is simple, we channel the rainwater from the gutters into storage tank/s. The rainwater is pre cleaned before entering the rain tank using a rain filter. Once stored, an automated controller supplies the rainwater on demand to where it is required, using an electric pressure pump.
The amount of water available for collection depends upon your area’s rainfall, the roof size , drainage efficiency, and the efficiency of the filter being used. Multiplying the roof area in metres, by the rainfall in millimetres, will give you the litres that can be captured.
200m2 x 20mm = 4000L
- Econo RainharvesterOpen or Close
This rainharvester collects rainwater from your roof and pipes into a rainwater collection tank situated under the eaves of your roof. It consists of one Leaf Eater Rain Head connected to one gutter downpipe. This flows through a First Flush Diverter, which removes the first flush of dirty rainwater from your roof to ensure the collected rainwater is of a high quality.
It is then piped into a 750 liter (or optional 2500 liter) JoJo water tank that has one tap outlet that can be connected to a hosepipe or optional gravity fed drip irrigation pipe.
- Mega Rainharvester – IrrigationOpen or Close
The Mega Rainharvester is designed so that your rainwater tanks can be hidden anywhere in the garden, rather than right next to the house. These can be both above ground as well as below ground rainwater storage tanks. Rainwater captured from the roof is channelled into underground pipes that lead to the JoJo water tanks or similar. This design allows larger volumes of rainwater to be captured. A pressure pump is connected, capable of supplying the rainwater to an irrigation system. This rainwater can also easily be used for toilet flushing and dishwasher/washing machine use if plumbing permits.
- Mega Rainharvester Whole HouseOpen or Close
The Mega Rainharvester is designed so that your rainwater tanks can be hidden anywhere in the garden, rather than right next to the house. These rainwater tanks can be both above ground as well as underground tanks. Rainwater captured from the roof is channelled into underground pipes that lead to the JoJo water tanks or similar. This design allows larger volumes of rainwater to be captured. A pressure pump is connected, powerful enough to supply your entire house and irrigation. The rainwater flows through a 3 stage water filtration system to ensure it is of a potable standard. A manual switch over (or optional automated) system easily allows you to switch back over to municipal water.
This type of system allows the best payback period as most of the municipal water is replaced by rainwater. Add a greywater recycling system to your property and you’ll get double use from your rainwater. This can help you further improve your water savings.
- Rainwater Harvesting FAQ’sOpen or Close
How much rainwater can I gather?
Roughly, for every 1mm of rainfall that falls per 1 m2, 1 litre will be captured. A 160m2 roof, with an annual rainfall of 700mm will capture around 121 600L.
What can I use harvested rainwater for?
Rainwater can be used for anything and everything. It can be used for toilet flushing, pool filling, car washing, clothes washing (the soft water gives a cleaner wash), showering, bathing, irrigation and even drinking.
Does the water need to be filtered?
Sometimes. If the water is only going to be used for irrigation then it may not need filtering, if the rainharvesting system has been designed correctly. If the water is going to be plumbed inside your house then filtering will be necessary. This is to help protect appliances like washing machines and dishwashers from getting clogged. If you wish to drink the water then filtering is essential as well as sterilization to remove potential bacteria etc.
What differentiates your rainharvesting system from other systems?
Briefly, the highlights of our installation are:
- We mosquito proof the whole system from rain gutter to tank and all overflow/ inlets.
- We place self-cleaning rainheads on gutter inlets to prevent leaves from entering the tank/s (reduces tank maintenance).
- We use first flush diverters to get rid of the first bit of dirty water, which DRAMATICALLY improves the quality of water in the tank.
- We install an Auto Tank Vacuum System that siphons dirty stagnant water from the bottom of the tank if the tank overflows. This reduces tank maintenance and gives a better changeover in the life cycle of the water in the tank. It also allows air to move across the surface of the water.We supply a tank gauge to allow you to see at a glance how much rainwater you’ve collected or used. This gives you a better understanding of what water volumes/ usage is all about.
What happens if there’s no rainfall?
This is bound to happen at some stage. We plumb either a fixed or variable municipal top up into your tank to give you “back-up” water when the rainwater runs dry. In non rainfall season we can increase the volume in the tank in case of municipality water disruptions. There is also an easy to use manual switch-over valve that allows you to switch back over to municipal water if you so wish.
How does a rainharvesting system pay itself off?
There are many variables that determine this. If you were never watering your garden before and now install a rainharvesting system to irrigate your garden then savings would be minimal as you’re not replacing any water. Rainharvesting systems pay themselves off better, the more municipal water you replace. This means you will get the most benefit from using rainwater in your whole house. By using rainwater for irrigation only, you save around 50% during the rainy season. By using it for toilet flushing, you save around 70% during the rainy season. By using it for your hot water system, you save around 80 – 90% during the rainy season. If you use it for drinking as well, you can get close to 100% saving during the rainy season.
Obviously it doesn’t rain for the entire year so costs/ savings need to be apportioned over the entire year. Here is an example; In Johannesburg on average it rains around 750-800mm per year (SA Weather 1971-2006). If we take a roof collection area of 240m2, you would capture around 190 836 litres. If we calculate that your household uses around 1000 litres per day, then you would use 365 000 litres per year. This then breaks down to around 187 430 litres of rainwater being used and around 177 570 litres of municipal water being used throughout the year. This works out to municipal usage being only 48% of your total usage. Next take your yearly municipal water bill and work out what 48% of it is and this is how you can see your potential yearly saving.
You need to also bear in mind that most municipal water billing works on a sliding scale so as your water usage increases per month, so your bill increases. The first bit of water per month is charged at a lower rate per kiloliter used. This then increases on a sliding scale. If you are using rainwater and only need a small municipal top up, that top up may fall in a lower kilolitre usage rate, which may produce additional savings.
You can then simply work out the quoted cost of the system, how much you save per year and thus how long the system will take to pay itself off. Bear in mind that this is worked out on today’s water prices. As water scarcity increases and water infrastructure fails, so municipalities will increase the price of water. Your savings would then accelerate.
You can make even greater savings by reducing the amount of water that you consume. There are many examples of how to do this but the two greatest savings are to reduce the amount of water you use for showering and reducing the amount of water used for toilet flushing. Some shower heads use up to 25 litres per minute. You can test this simply by running the water into a bucket for 15 seconds, measuring the volume in litres ad multiplying it by 4. If you change these out to a low flow shower head your usage can drop to between 6 – 8 litres per minute. Speak to us about replacing your shower heads. Older toilets can use in the region of 9 litres per toilet flush. You can reduce this amount by upgrading to dual flush cisterns, putting a plastic water bottle (the only thing they’re good for) filled with water and sand into the cistern or installing a Reduced Flush Toilet Flusher. Our Reduced Flush Toilet Flusher lets you decide how much water you want to use per flush.
What are some benefits of using rainwater?
Significant economic, social and environmental benefits can be achieved by using rainwater. By using Rainwater Harvesting systems to supply water for some, or indeed all of our requirements, you can reduce your dependence on mains water. Our water supplies are falling and water restrictions are in place in many communities to reduce our overall water usage and protect our supplies. There is no better quality water available naturally than rainwater. Some say there are health benefits to using rainwater which is not treated with chemicals like our mains water is. Rainwater falls for free – once you have installed a rainharvesting system, you use less mains water and can reduce your water bills. Local municipalities will increase water prices as they look to recover the true costs of providing water to the community.
The cost to the community to supply mains or reticulated water services is becoming more expensive every year. The construction of dams, pipes and treatment plants is huge and ultimately as tax and rate-payers, we foot this cost. Rainwater Harvesting reduces the significant damage to our rivers, water habitats and organisms caused by stormwater runoff.
Will I need a pressure pump?
If you wish to top your swimming pool or pond up and the tank is higher than them or if you wish to use a bucket or watering can, then the answer is no. Otherwise if you have or wish to use an irrigation system or if you want to pump the water into your house, you will need a pressure pump. Don’t worry, we size the correct pump to give you the pressure you need. This pump switches on automatically when a tap is switched on and will automatically switch off when the tap is closed.