Temperatures are beginning to rise which means summer is on its way. With the warmer weather, you may be planning to spend more time outdoors, enjoying the heat. Along with the longer days, comes the prospect of thunderstorms. While a sudden shower would delay your outdoor activities, it presents the opportunity to adopt a greener living habit—harvesting rainwater.
Last summer water restrictions were put in place as South Africa was in the grip of a drought. Many communities were forced to rely on the kindness of strangers and organisations to supply them with clean water for drinking and cooking. Harvesting rainwater reduces the demand on the municipal supply and supplements your need on municipal water.
What are the benefits of harvesting rainwater?
Installing a rainwater harvesting tank on your property makes a significant difference to you, your community and the planet. Greener living really does benefit everyone.
- Saves you money
The water collected in a rainwater harvesting tank is available to flush your toilets, water your garden, wash your car and in your washing machine. Although it’s not fit for human consumption unless you filter it first, using rainwater for general purpose cleaning and irrigation reduces your reliance over the year on mains water by up to 60% and thus cut your water bill accordingly.
- Minimises the impact on local storm water infrastructure
During the thunderstorm season, it’s not unusual to see rivers of water flowing down your street and into storm water drains. That’s because our paved and tarred areas don’t allow for the rainwater to be absorbed back into the ground.
The excess water places a strain on the drainage system and increases the chances of flooding. By harvesting rainwater and releasing it back into the natural water course, this helps minimise the strain on your local municipality.
- Saves precious resources
Harvesting rainwater achieves several green living principles. You’re saving potable water which is a valuable resource. That makes water available to other communities who need it. At the same time, you’re reducing your carbon footprint. Water has to be pumped around to the cities and towns where it’s needed which means it uses electricity. By harvesting rainwater, you reduce the amount of power used to supply your home with potable water.
With all of these benefits, it’s no surprise that eco-friendly homes incorporate rainwater harvesting tanks into their designs. Rainwater harvesting makes a definite contribution to the planet, saves homeowners on their monthly utility costs and stretches water supply, though marginally, even during times of drought.
If you’re keen to make rainwater harvesting a part of your lifestyle, you have two choices. You can either buy one of the eco-friendly homes currently on the market or install a rainwater collecting tank on your existing property. Let’s take a closer look at these two options.
Rainwater harvesting and eco-friendly houses
The trend towards green living is growing in South Africa. More and more developers are aware that homeowners are looking for properties that are cheaper to run and kinder to the environment. Eco-friendly houses typically include several green features that achieve this.
Photovoltaic solar panels and insulation keep energy costs down. Underground rainwater harvesting tanks ensure a supplemented supply of water. Eco-friendly building materials reduce environmental impact. Eco-friendly homes require less maintenance, cost less to run and provide families with a healthy and comfortable lifestyle.
Eco-friendly houses are more expensive than traditional homes. And with the money you save on maintenance and running costs, it’s possible to recoup your initial investment within a few years.
Buying a rainwater tank for your home
You don’t have to buy an eco-friendly house if you want to harvest rainwater. It is possible to retrofit your existing property with a tank, and it is affordable. Here are some things to consider if you want to buy a rainwater harvesting tank and start living green.
How to choose a water tank
It’s more efficient to have one large water tank rather than several smaller ones. Determining the size of the rainwater tank that will provide for your needs depends on the rainfall in your area and the size of your collection area (roof size).
- Calculating the collection area
A general rule of thumb is that 1mm of rain falling on 1m2 will deliver 1 litre of water to your tank. Measure the size of your roof and you’ll have an idea of how much rainwater you’ll harvest.
- Working out the size of the tank you need
How much water does your household need? Think about how many people live on the property and what you’ll do with the rainwater you harvest. Rainwater tanks come in many sizes – broadly classified as follows:
- Small tanks hold less than 2000 litres
- Medium tanks hold between 2000 and 10000 litres
- Large tanks hold more than 10 000 litres
Don’t forget to take your local climate conditions into account. In South Africa, different regions get most of their rain either in winter or summer. If the rainwater you collect will be used to flush your toilets or feed your washing machine, then you’ll want a rainwater system that automatically switches over to the municipal supply when the tank drops below its threshold. Research green living ideas to help reduce your household water usage.
- The best place for your tank
When you’ve worked out the size of the tank you need, you’ll need a place to install it. Underground water tanks are common in purpose-built eco-friendly houses. That’s because underground water tanks take up less space, last longer and produce a better quality of water. Subsoil conditions would need to be ideal if you want to install your water tank below ground.
Above ground water tanks are easier to fit, they’re exposed to the elements which affect their lifespan. Place your rainwater tank to best use gravity so water flows into the tank. If this is not possible, then a pump is required to push the water to the tank.
You should try to place your rainwater harvesting tank under some form of shelter such trees or a roof. By limiting its exposure to sunlight, you’ll reduce the temperature fluctuation and extend the life of the tank.
- Choosing the right material for your water tank
Water tanks are made from a wide variety of materials. Light shouldn’t enter the water tank so prevent algae. Choose a water tank made from solid, opaque material.
Polyethylene water tanks
Polyethylene is a tough plastic used to make water tanks of varying sizes and colours. They’re affordable and attractive which makes them ideal for use in existing gardens. If the polyethylene is reinforced, the tank is made for underground installation. Though the material itself doesn’t conform to green living principles, it is used in a way that benefits the environment overall.
Although they are robust and require little maintenance, the material is susceptible to UV damage when exposed to the sun for long periods which means they’ll need replacing at some point. If the tank is painted appropriately or installed under some form of shelter, its life is extend. It’s worth paying a little more for a high-quality polyethylene as these tanks have built-in UV protection.
Fibreglass water tanks
More expensive than plastic tanks, fibreglass water tanks are not easy to find in South Africa. They require precise installation because they cannot tolerate any soil movement.
Galvanised steel water tanks
Steel water tanks are better suited to greener living commercial applications. They hold more water than plastic tanks. They are prone to rust, so if potable water is required, the tanks need to be lined with a membrane.
Concrete water tanks
Concrete water tanks could last u a lifetime. They’re durable but expensive. They provide the best storage conditions for rainwater. Concrete neutralises the slight acidity of rainwater which improves its quality. It’s not biodegradable, so not a good choice for those who want to follow green living principles.
The disadvantage of using concrete water tanks is cracking and leaking. Before installing a concrete water tank underground, best to consult civil and geotechnical engineers. The soil conditions need to be suitable and the installation perfect to decrease the risk of cracking. These tanks need to be waterproofed to reduce the risk of leaking.
Pre-manufactured concrete water tanks are available too. They come in sections for quick and easy installation underground in modules to provide for required volumes.
Protecting your rainwater supply pipes
Pipes installed underground need to be of the appropriate code and specification and require additional protection against heavy vehicles. Pipes above ground require support or they will crack and break when filled with water. Paint appropriately to protect them from sun damage. Or pipes with built-in UV protection are best suited.
Installing an overflow pipe takes excess water to natural light. Water tanks overflow several times a year so the water flow needs to be correctly designed. Uncontrolled overflow could cause unwanted damage.
Adding a pump to your rainwater tank
Your rainwater tank will need a pump to help you achieve the right water pressure. A water tank installed 2m above the tap and filled with 2m of water will only produce a discharge pressure of 40kPa. Normal household water pressure ranges from 250kPa to 400kPa. So your rainwater tank needs a pump to help achieve the required water pressure.
Cleaning and maintenance
Rainwater tanks need a screen to stop debris and organic matter such as leaves and bird droppings from contaminating water supply. A first-flush device is recommended for diverting the first rainfall after a dry season away from the tank. The collection area needs to be clear of leaves and debris.
Tanks require inspecting for an accumulation of sludge at least every 2-3 years. This requires emptying and rinsing completely if necessary. Professionals could be used to clean tanks and make sure that the water supply is correct.
Depending on the rainfall in your area, it is possible to harvest rainwater for various needs. When harvesting rainwater, you realise how green living supplements your water needs. Using water wisely is one feature of eco-friendly living. Whether living in an eco-friendly home or implementing this feature at a conventional house, goes to show, anyone can enjoy the benefits of harvesting rainwater, financial and otherwise.