What types of home watering systems are available?
- standard drip systems.
- standard sprinkle/spray systems
- drippers embedded in pipe
- weeping hose
- Wobbly Tee type low pressure irrigation
- traditional hand held hose
- traditional lawn sprinkler on a hose.
What are the advantages and disadvantages of the different types of watering systems?
- Traditional hand held hose
- No initial setup time
- Cheapest method as far as equipment cost is concerned
- Standard drip systems. These consist of a pipe (usually 13mm polypipe) laid out in the garden
and some 4mm pipe connected to this at various points. The 4mm pipe has drip irrigation fittings fitted to it.
- Usually considered the most water
efficient method of watering, since water is delivered to the roots of the plants rather than the leaves.
- Currently still permitted under Sydney's water restrictions.
- The most time consuming system to set up as a dripper is generally required for each plant.
- Fairly expensive due to the large number of fittings required.
- Some drip irrigation systems become clogged easily. An in-line filter can help. Also the use of one-way valves in
appropriate positions may be of assistance. However, it is
still then possible for them to get blocked and so periodic checking may be required.
- Drippers embedded in pipe are a relatively new system. These consist of a flexible pipe of 13mm diameter with drippers embedded
every 30cm or so (depending on brand). Compared to standard drip systems, these are easier to install because you merely need to lay down the
pipe. For most applications this method is not quite as efficient as standard drippers as with this method there is no precise placement
of each dripper... however this is generally not too bad a thing as the design of a watering system is to water the roots, not the plants...
and usually the roots of plants do extend out to cover the garden. This is the option with the highest start up cost, but I have found so
far to be the most regarding in the end.
- Standard sprinkle/spray systems have some advantages as well. Whilst perhaps lacking in general efficiency (watering the leaves, rather than the roots), some plants do prefer to receive some water through the leaves and air and hence prefer sprinkler systems. These are easier to install than
standard drip systems as each sprinkler covers a larger area than a dripper. Some water is also often wasted in these systems do to water
spraying onto paths and driveways.
- Weeping hoses are like drippers embedded in pipes, except that they are designed to be moved around the garden. This makes them quite cheap for
an initial investment, but do require ongoing effort.
- Wobbly Tee systems produce rain like watering without the pressure requirements of traditional sprinklers and with the potential of less evaporation than traditional sprinklers. Some readers of this website are big fans of the Wobbly Tee, but I haven't had the chance to try them as yet.
How much of my garden can I water at once?
At our place, using Sydney water, we can get about 20 litres per minute from our taps. You can measure this for yourself
using a bucket and watch. In order to allow for pressure loss, we tend to aim to use about 15 litres per minute or so
from each zone. Also do remember that different areas of your garden may have different watering needs... some plants
require more water than other plants and some areas of the garden will be more shady than others.
- hand-watering and traditional lawn sprinklers generally take up most of the available water flow when in use.
- standard drippers use about 4litres per hour. If we are aiming to use 15 litres per minute (900 litres per hour) then
we can have 200 drippers per line. This is a large number! Each zone will need to be watered for an hour or so at a time.
Note that if you are approaching that large a number of drippers, you may wish to fork your line into 2 pipes near the tap,
or use 19mm poly-pipe pipe, do reduce friction losses. 200 drippers can cover 200 small plants or 50 large plants. The area this
covers will depend on how densely planted your garden is.
- drippers embedded in pipe often use as little as 2-4 litres per hour... allowing for 200-400 drippers! In order to reduce pressure
losses I run 19mm poly-pipe pipe around the garden, then use Ts to have 20 or 30 meter runs of the dripper pipe. Personally I have zones
which have over 100 meters of dripper pipe in this way which work well. Of course, if you place 100 meters of piping around a garden
at 30cm intervals then you can cover 30 square meters of garden bed.
- sprinklers use more water per item, but each sprinkler covers a wider area. These vary greatly in water flow and area covered,
so do read the instructions carefully. In order for one zone to cover the most area, aim for each sprinkler to cover the most
area while using the least water! I find that one zone can cover about 100 square meters of garden bed quite effectively.
How much and how often should I water
This depends on rain and temperature as well as the type of plants that you have. I find the best way to think
about amounts of watering is in mm-of-rain-equivalent. In other words, how much rain do I need to not use my watering system,
and if we get a little rain, how much watering do I need to do.
During different times of the year it is generally best to vary the frequency of watering rather than the amount. This encourages
better root development, and less dependence on your watering. On a hot summer's day I will try to water the garden once a day,
in winter once every week or two. Naturally pots dry out faster and can be watered more often. When it rains 10mm or more I consider
that the rain has done a watering for me and I reset the counter, so to speak.
For optimal plant conditions it is best to water the plants about 10mm equivalent each time you water (this corresponds to 10 litres
per square meter). For a zone that uses 15 litres per minute and covers 30 square meters (eg drip line) this equates to about 45 minutes
to an hour of watering, which is about what the manufacturer recommends. You can calculate the flow of a zone by adding up the flow
of each watering item (sprinkler etc) or by measuring what your water meter does in a minute (assuming nothing else in your house is
using water at that time).
Unfortunately that optimal method uses a fair bit of water! On a quarter-acre house block (about 1000 square meters) a house may cover 200-300
square meters of ground, a driveway and paving 50-100 square meters... leaving at least 600 square meters of garden.
One full watering would use up 6kl, or $6 of water (about 6 hours hand-watering)! This is a lot! Hence I do my best to not water areas of the garden that don't need much
water (lawn, natives, succulents etcetera) leaving only a small proportion to receive this rate of water (particularly in the water restrictions)!
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