Commercial Rainwater Harvesting

What is rainwater harvesting?

Rainwater harvesting is the simple process of collecting and storing rainwater that has run off your rooftops, guttering and open ground within your business premises.

The rainwater is then stored and filtered, ready for your business to use.

Many different rainwater harvesting systems are available – from rooftop systems to surface runoff systems; these can be tailored to the type of property you work from and your business water needs.

How does a rainwater harvesting system work?

There are different types of commercial rainwater harvesting systems, but in general, a rainwater harvesting system works by collecting rainwater and depositing it into a storage tank.

Initial filtration occurs on the collection before the water reaches the storage tank removing any debris such as leaves and dirt particles. Water is then pumped when initiated through the second stage of filtration called sedimentation and into a control unit, which is used for the final stage of filtration.

After final filtration, the water is stored in a “Buffer Tank” until there is a need to use it. When there isn’t enough rainwater in the tank, your mains water supply is used to top-up the remaining water.

There is a fourth part to the process, which is optional and entirely depends on what you’ll be using your harvested rainwater for – this is a UV disinfection unit.

This unit is used to kill bacteria and is essential for any food and drink production, or if used in your showering facilities, for example. Other businesses may use this as peace of mind and will only use the water, for example, for general use.

The filtration processes in rainwater harvesting will ensure your business uses the cleanest rainwater possible whilst reducing your overall water consumption.

The different types of commercial rainwater harvesting systems

Here we break down the different types of commercial rainwater harvesting systems:

Water Butt

This is the simplest form of rainwater harvesting. Water is collected from natural rainfall, roof runoff and drainpipes. There’s no filtration process, so the water cannot be used as a substitute for mains water. However, you can insert a small filter to get better rainwater for tasks such as watering your lawn with a sprinkler system.

Direct-Pumped (Submersible)

This is generally the most common commercial rainwater harvesting system; it’s simple, easy to set up, and perfect for small to medium-sized commercial properties.

The pump is located in the underground tank, the harvested water is then pumped to the desired location, whether it’s the toilets or your food production line.

The mains water will top up the tank when it is running low to ensure no supply interruption.

Direct-Pumped (Suction)

Direct-Pumped (Suction) is different to the “Submersible” version as the pump is not inside the tank but within your premises control room – usually an appliance or utility room.

The control unit will also deal with the backup water from the mains supply.

Indirect Gravity

This system harvests rainwater initially pumped into a high-level tank and supplied to the individual outputs by gravity alone.

Due to this setup, the pump will only need to work when the high level (Header) tank needs filling. The water mains will also feed directly into the high-level tank.

Indirect Pumped

This setup is similar to the indirect gravity system, except the internal tank can be at any level in the building as this setup does not rely on gravity to pump the water through the building.

It has a booster pump that pumps the water around the building. The booster pump also offers increased flexibility, as it can be tailored to suit the flow of the premises.

Gravity Only

Occasionally, you can have a system that can rely entirely on gravity and requires no energy input. The arrangement of this system is explicitly designed to allow gravity to do all the work.

This will only work if the storage tank is stored below the level of the gutters and other water collection systems.

If possible, it will only be powered by gravity and can be an incredibly efficient option and reduce water consumption and energy output.

Which rainwater harvesting system should I choose?

The system which suits your business needs to most very much depends on the set up of your business property. Rainwater harvesting systems will need to be set up correctly to work efficiently.

We recommend talking to a consultant to review the specific needs of your business.

How much water can be saved by rainwater harvesting?

Harvesting rainwater can reduce your overall water consumption by 40%. It will dramatically reduce your overall water costs and allow your business to operate in a more environmentally friendly manner.

Overall it depends on how much water you use, but by having a solid harvesting process in place, you’ll reduce your water consumption dramatically over time.

What are the benefits of rainwater harvesting?

There are plenty of benefits of using rainwater harvesting, from reducing your impact on the environment to saving huge amounts on your water bill; rainwater harvesting has plenty of benefits:

• Harvesting rainwater moves you closer to achieving your BREEAM certification.
• Reduces your overall water consumption.
• Improves your overall impact on the environment.
• Rainwater systems are incredibly cost-effective.
• The systems are easy to use and simple to implement.
• Tailor the harvesting system to your business needs.

What can harvested rainwater be used for?

Harvested rainwater can be used for a range of processes for a business, from core production to everyday toilet facilities; harvested water can be used for a lot of different functions. Here are a few of the key functions:

• Toilet flushing
• Irrigation
• Food and Drink production
• Vehicle washing
• Urinal usage
• Cooling
• Drinking water for livestock
• Sprinkler systems
• Clothes production

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