Rainwater tanks are an excellent means for harvesting and storing rainwater for use instead of the main water supply. For any purpose ranging from watering gardens, and houses to drinking, rainwater tanks present considerable environmental and cost advantages. In this blog, you will read about the working of rainwater tanks, the advantages of using rainwater tanks, how to choose the size of the tank, and where you can place your tank. We also highlight some installation tips and rules and regulations concerning the use of rainwater tanks.
Stepwise Rainwater Tanks Functionality
Rainwater tanks can be defined as a reservoir for storing rainwater from your roof and using it later on. Here's a step-by-step breakdown of the process:
- Rainfall Collection: When it rains, droplets fall on your roof, and this may be made of either metal or tiles. It is channelled through the roof and falls and is collected in a gutter. The roof gutters are purposely arranged to hold the rain and direct it to the downpipe.
- Gutter and Downpipe System: Gutters are tied to downpipes that, in turn, channel the water off the roof to a filter. Some systems have provisions for stoppers called leaf guards or first flush dividers to allow only clean water into the tank.
- Filtration: Sometimes to prevent large materials such as leaves, twigs or dust from clogging the tank, the water is first filtered before it is piped to the tank. Secondary and tertiary systems are sometimes added to a more comprehensive purification of water especially for uses that are going to be in potable (drinking) form.
- Storage in the Tank: The filtered water is then directed into the rainwater tank. When water is pumped into the water tank, the float rises and activates the water pump thus flowing the water into the rainwater tank. They are of different types, and capacities and are made from plastic, steel material or concrete depending on the amount of water you intend to store and the space available.
- Water Use: After the water has been filtered the water can be pumped or sometimes gravity used to supply your household or your garden. A plumbing system, it is able to provide water to toilets, and washing machines among other facilities and for drinking (depending on the water treatment process it has undergone).
- Overflow: If the rainwater tank is full, any surplus water is generally discharged into a gully or a garden through an outlet so as not to harm the tank.
There is highly significant variability in the conceptual form and architecture of rainwater tanks; however, they are typically designed to capture and clean rainwater while storing and distributing it as needed.
Environmental Advantages of Rainwater Tanks
Several factors make rainwater harvesting an environmentally friendly practice. Here are a few of the most significant environmental benefits:
- Water Conservation:
When you use rainwater you can decrease the use of piped water which is from your local water supplier. The use of rainwater harvesting in cases in the region that is characterized by drought or a low supply of water is environmentally friendly. It is a practice that goes a long way in protecting surface and groundwater resources to avoid the effects of over-extraction of water from natural sources such as rivers and aquifers.
- Reduced Stormwater Runoff:
These storm waters take in the forms of surface runoff from different hard surfaces like roads and rooftops whenever it rains and in the process they integrate oils, trash, and chemicals into local waters. Since rainwater is collected in tanks tapping into this resource means minimizing runoff which is likely to harm the environment and the water sources.
- Lower Energy Consumption:
Depending on the constituents of the water and the distance over which the water has to be transported, both water treatment and distribution processes consume a lot of energy. The conservation of rainwater for uses other than potable uses means that less water will be demanded and treated, and the energy used in pumping and treating the water will be reduced.
- Less Pollution and Erosion:
Rainwater harvesting water tanks help offload people’s reliance on stormwater systems, thus controlling floods, erosion, and water source pollution. This in return assists in the conservation of ecosystems, biodiversity and water in the local areas of the world.
- Natural Fertilization:
Still, water is softer than tap water which has undergone chemical treatment and contains substances such as chlorine and fluoride. Rainwater is preferable to tap water for watering plants since it is more natural in most ways than tap water.
How to Determine the Right Size for Your Rainwater Tank
The size of the rainwater tank depends on; rainfall intensity, roof area, number of people in the household, and intended uses of the water. Below is a guide to help determine the appropriate size of a rainwater tank:
- Roof Size:
The amount of rainfall that you can harvest depends on the size of your roof. Larger roofs will collect more water which in turn means a larger tank and ability to hold water for a longer time between two consequent rainfalls. To determine how much water you can harvest from your roof, measure how many square meters of roof space is available then multiply this by the rainfall amount typical of your area. For instance, a roof of 100 square meters situated in an area where the average annual rainfall is 800 millimetres could harvest up to 80,000 litres annually.
- Water Use:
Think about the amount of water consumed by your household. For instance, if you are using the rainwater for watering plants or washing toilets a smaller tank may be adequate. If you plan on using the rainwater for drinking and washing, you will have to harvest more in a large tank. You should also look at the frequency of the rainfall and how long your family can withstand without any rainfall.
- Rainfall Patterns:
Environmental factors also influence the size of the tank, especially the climate of the region where you stay. Where there is steady precipitation the above-mentioned tanks may suffice for your consumption standards. But in arid regions or situations where the rainfall is irregular, you will use larger tanks to get enough water for the dry seasons.
A common rule of thumb is to have a tank size that provides storage capacity for one to two month’s worth of water usage for your home; however, the above factors must be taken into consideration.
How Much Water Do You Use?
The size of the rainwater tank will largely depend on the use of water in your household so you should be aware of how much water is used. Water usage per person, per day, for every household is roughly 100-150 litres. Here are some estimates for common water uses in a household:
- Toilets: 30-50 litres per day
- Showers: 50-70 litres per day
- Washing Machines: 20-40 litres per day
- Dishwashing: 10-20 litres of water every day
- Small gardens: 200-300 litres of water per week
- Large gardens or lawns: 300-500 litres of water per week
How Much Water Can Your Roof Collect?
The amount of water that can be retained by your roof depends on the roof size and the intensity of rainfall in your region. The material used in placing the roof also determines the quality of the water that is harvested. For instance, metal roof structures are rapid in shedding water and therefore are recommended when it comes to rainwater harvesting. On the other hand tiled or concrete roofs might accumulate debris on them and hence need the water to be cleansed more often.
To get an estimate of how much water you can collect, you can use the following formula:
Rainwater Collected = Roof Area (m²) × Average Rainfall (mm) × 0.8 (for efficiency)
The efficiency factor has consideration to loss due to evaporation, overshooting or filtering.
Choosing the Best Location for Your Rainwater Tank
The location of the rainwater tank is very important to get the best out of it throughout its service. Here are some factors to consider:
- Proximity to the Collection Surface: Regarding installation, the tank should be situated as close to the downpipes as possible to also minimize the cost of plumbing. This check prevents water from the roof from having to overcome certain barriers before reaching the tank.
- Level Ground: The tank should be installed in a levelled area to allow for stability, and to conform with proper water circulation. Another advantage of a steel tank with a stable surface is that it can’t tip over or warp on the ground.
- Shade: If space allows it, position the tank in an area where it will not be exposed to direct sunlight, to reduce the likelihood of the tank developing algae. In a direct sunlight case, it is easier for water in the tank to heat up making it vulnerable to different forms of contamination.
- Accessibility: If constructing the water tank the tank should be well placed in a way that it can be easily reached when cleaning or checking water level.
- Distance from Plumbing System: The tank should ideally be positioned close to where the water is going to be used for example a garden faucet, washing machine, toilet etc.
Rainwater Tank Installation Guidelines in Australia
In Australia, installing a rainwater tank is relatively straightforward, but there are a few important guidelines and regulations to consider:
- Council Approval: Regarding the local council regulation, you may require a permit to put up a rainwater tank. Before one moves forward, it is always useful to contact the local authorities to understand the legal aspects such as the building codes and zoning ordinances.
- Water Quality Standards: If you intend to use the harvesting water for drinking or food preparation purposes you need to make sure that the water meets the standard water quality in Australia. This often means that they need a more complex filtration and treatment system for example an Ultra Violet sterilizer or water purifier.
- Plumbing and Connections: An expert plumber is usually needed to install your rainwater tank to the main water supply of your home. Several Australian houses now have rainwater and mains integrated systems where the rainwater tank is the main water source for other uses apart from drinking.
- Maintenance: The tank and system installations are supposed to be checked often for maintenance. This ranges from cleaning of filters, examination of the condition of the first flush diverter, and examination of the tank for the formation of algae as well as the gutters and the downpipes.
- Safety Considerations: Tanks should be properly anchored to minimize contamination or damage. It is recommended that the tank must be adequately and sufficiently covered to prevent the breeding of mosquitoes and that appropriate provisions for handling large volumes of rainfall.
Conclusion
Rainwater tanks are a definite effective aid in the management of water, decrease effects on the environment and are a reliable source of water, particularly for non-portable uses. When properly designed, properly sized and properly installed, a rainwater tank system is a win-win for the person paying the bills and for the planet. These environmental benefits are only water saving and combating the menace of runoff, making rainwater harvesting a basic and effective incremental move towards change.
