Garden Irrigation – Small Scale Garden Watering Projects From Your Rain Barrel

What is a WaterWand Heliomatic?

It is a very small solar powered pump designed to use stored rainwater from rainwater barrels or tanks. It works automatically, watering more when it is sunny. It starts automatically every 3 hours and pumps in proportion to the light intensity in the previous 3 hours.

Okay, so what can it do?

Typically it will pump about 130 millilitres a minute. Maximum pressure is 3 bars – that is a lot for such a small pump and it means that lifting water 5m is not a problem, so hanging baskets, upside down tomato plants and similar things are in easy reach.

The Heliomatic can be used with low volume irrigation systems – it is designed for use with 1 litre per hour drippers and 8mm seep hose, both of which can be supplied as optional kits.

How many drippers?

This really depends on what you are watering. The more drippers there are on a system, the less water will come out of each one. The absolute maximum is 40 – in this case the irrigation system needs to be level and needs to be fed from the centre or as a ring main to ensure even distribution. The Heliomatic 130 would supply enough water for 40 typical 5 litre pots, the Heliomatic 250, with a bigger solar panel 40 10 litre pots.

Where it is not possible to have a level irrigation system there are a couple of options: –

  • reduce the number of drippers
  • Use flow regulators. Up to six two litre per hour pressure compensating drippers can be used to supply submains with up to 5 low rate drippers on each. The drippers on each regulator will need to be kept level, but the regulators can be at different heights without causing any problems. Great where you have a few pots and a few baskets.

What about seep hose? (aka soaker hose, weep hose)

Only the small bore (8mm diameter) seep hose is suitable for use with this solar watering pump. On a level site the pump will supply about 6m of seep hose. On sloping sites the tube should follow the contours to give the best water distribution. Another option is to supply a number of shorter lengths through flow regulators (also known as pressure compensated drippers or pcp drippers). In this case each length should be laid along the contour, but different lengths can be at different heights without causing problems. As a guideline, 6 flow regulators each with 1m of seep hose tube can be used with up to 2m difference in height between the highest and lowest.

Multiple seep hose systems. You can install a number of permanent seep hose systems, each with up to 6m of seephose. These are then connected to the pump on a rotational basis; for example put a seep hose down each of 7 rows of vegetables and connect each one to the pump for one day a week.

Mixed irrigation systems

It is possible to devise irrigation systems with both seep hose and drippers. Even if there are significant height differences this can still work.

To do this up to 6 flow regulators are attached to the distribution pipe. If required these can be at different heights. A sub distribution main, or a length of seep hose, can be attached to each. If a sub main with drippers, up to 6 drippers can be attached (these will need to be level) or up to 1m of seephose.

Rainwater collection and storage

The easiest method for collecting and storing rainwater is using a rainsaver and a water butt. This will work anywhere there is a roof to collect from and is so common that it doesn’t really need further discussion here.

A really discreet and attractive way of capturing and storing rainwater is by using specially designed raised beds. Rainwater storing raised beds are simply a raised bed with a reservoir beneath it. These can either capture water from roofs – just like a water butt, or they can simply capture the rain that falls on them and store it for future use. If you Google “rainwater harvesting raised beds” you will find them. They are also great for use where there is no soil, the soil is unusable, or where there are tree roots which suck all the moisture and goodness out of the soil.

Wells, springs and streams

Providing the water is clear, these too can be used to supply a WaterWand. Normally it is recommended that the water should be no more than 2m below the pump, but in tests pumps have worked successfully even where the water has been 4m below the pump. If you want to use these sources, make sure they are not contaminated, particularly by herbicides which will damage your plants.