A key component of all rainwater harvesting systems is the storage tank or tanks. And the debate about the relative benefits of above ground compared with underground tanks has been running for decades. The fact is that both have their strengths and weaknesses but this brief article focuses on the above ground tanks.
Why Use A Storage Tank?
A rain harvesting system kicks in while rain is falling but we need to store the water so that we can use it at other times. Even the most rudimentary systems in the past used either the time honoured water butt stood beneath the roof downpipe, or a system of underground cisterns carved from solid rock, for example like the Romans built. Nowadays, purpose-built storage tanks are both cheap and versatile and a very necessary component of every rainwater harvesting installation.
Common Type Of Above Ground Water Storage Tanks In The UK
Plastic tanks, in the form of polyethylene tanks and GRP (glass reinforced polymer) tanks are the most common nowadays for rainwater harvesting systems. Polyethylene (PE) is a very efficient low-cost option and is used in everything from watering cans to water butts and large tanks up to 30,000 litres volume. GRP tanks can be pre-insulated if required and usually have a larger capacity, typically up to 9,000 litres. GRP tanks can also be configured in a multi-sectional arrangement for even larger system storage capacity.
1. Easier Maintenance
It is obvious that any fixture that is installed above ground permits much easier access for repairs and maintenance than if it were buried below ground level. Having said, they may also be more vulnerable to damage in some situations. Tanks, pipes, pumps and other rainwater harvesting equipment should not leak if properly installed and maintained, but if leaks should occur they will be relatively easy to spot and to repair.
2. Ease Of Installation And Expansion
Smaller PE storage tanks can simply be placed on firm level ground, larger ones are better sited on a concrete or paved base. GRP tanks will require a solid level base as they are less flexible and can crack if there is any movement. In time, if it is decided to increase the system’s storage capacity, adding another above ground tank is generally very easy in most situations.
3. Variety And Space
There is a greater variety of above ground tanks available on the market than their below ground cousins. Such tanks vary is size, shape and style, ranging from simple round barrels to decorative imitation columns and even thin boxes made to look like fence panels. Because of this wide variety, space is generally not a major issue as there is usually something that will fit.
Disadvantages Of Above Ground Tanks And Considerations
Above ground tanks are exposed to the extremes of the elements. This means that in winter there is a risk of freezing, especially to pumps and pipework, so good external grade insulation is a must in most areas of the country. Or if the water is only used seasonally (e.g. garden watering) then the system can be ‘winterised’ by draining everything down fully to avoid damage. In summer, where tanks are exposed to full sunshine for much of the day, it is wise to provide some form of rudimentary shading e.g. screening with a fence panel or trellis with plants. This also helps to hide the tank from view if that is an issue.
The Right Decision On Storage Capacity
When it comes to considering which storage tanks is best suited to the rainwater harvesting system that you are planning, it pays to talk to the experts. We would be delighted to walk you through the options that we supply, together with the rationale behind each product type. Contact us today for a brief informal discussion and see just how well we can meet your needs.