setting up a rainwater catchment system

如果不是经济原因，你为什么要安装一个水箱?Here are some reasons:

  • To do your part for water conservation;
  • to be able to water your garden with some independence from water restrictions;
  • to use rainwater for laundry, showers and toilets;
  • for increased water independance.

What size of water tank should I choose?

Get the biggest tank you can fit in your garden. As a rule of thumb, about 25,000 litres of storage is considered enough for a small family to be nearly self sufficient for normal domestic usage. The storage size will vary according to local rainfall. Dry areas would require more storage, wet areas less.

A cheap and simple solution:

You can get started with rainwater collection by installing diverters in downpipes and filling a large garbage bin, but with this system there is no “first flush diverter” to remove impurities from the first quantity of rainwater from the roof. Water can be distributed from the bin/tank using gravity or a small pump.

Types of rainwater collection tanks

  • Cylindrical tanks– either plastic or galvanized iron are often the cheapest, but they require a lot of space.
  • Rectangular and other narrow tanks– either plastic or galvanized iron can fit under eaves and in narrow spaces next to fences. However, they are lower volume and more expensive.
  • Collapsible bladder systemscan be installed out of the way under decks.

Here's an interesting set up:

Rainwater Catchment Diagram

Other considerations:

  • If you use rainwater for showering, be aware of the difficulties matching different water pressures. The mains pressure is often higher than what a pump can produce and the mains pressure can stop the tank water from coming through the pipes.
  • 政府对水管和水箱水系统的连接有严格的规定。这样做的目的是防止水箱水系统可能污染总水管系统。持牌水管工必须安装这种连接。如果系统是单独探测的，这些规定就不适用了。
  • 灌满水箱的能力也取决于你所拥有的屋顶集水区域。如果集水区太小，你可能永远不会填满大水箱。这可以通过您所在位置和屋顶区域的平均降雨事件来计算。

Installation:

  • Larger tanks will often need to be installed in back yards using a large crane. This is easiest with new home constuction when sites are more accessible, it may be difficult with limited access.
  • 向坦克零售商查询使用起重机的费用。一些零售商会为超过特定尺寸的坦克提供免费的吊车安装，低于这个尺寸你可能需要单独支付吊车的费用，但这不应该是非常昂贵的，因为在大多数情况下这可能是一个非常快的过程。
  • Tanks can be partially buried – up to a third the height of the tank is usually possible. If you bury tanks deeper than that without taking special measures they can “pop out” of the ground if the tank is empty and the water table rises. A drain system around a buried tank site with a sump and water pump installed could avoid this happening and enable the tank to be more fully or completely buried. This type of installation should be done professionally.
  • Ensure that every tank has a valve installed at its outlet. This will allow you to isolate the tank quickly and easily to work on the pipe system. Also, if you damage the pipe outlet system you can shut the valve to prevent the entire contents of the tank being lost.
  • 如果支撑结构设计为在甲板下留出空间以容纳油箱，则油箱可以安装在甲板下。
  • All tanks must have an overflow connection to stormwater (or perhaps another lower tank).
  • Choose your water pump carefully – it is very important to calculate the pressure and flow required to get the appropriate performance.

Check out theEcohome green building guide pagesto see ourIntroduction to rainwater harvesting, tolearn about water efficient fixtures,grey water recycling,water saving showerheadsand all about green home building atNorth America's free green building website, Ecohome.

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