Tool 5.2 Stock water requirements

Tool 5.2 Stock water requirements

The best way to manage and maintain stock water is to have reliable information about your property’s water supplies. This means knowing where the water is, how much is available and whether it is ‘fit for purpose’. A water stocktake will provide this vital information.

Farm water comes from a number of different sources. These may be natural sources such as rivers and channels, or they may be constructed in the form of dams, ground tanks, wells or bores. Whatever the sources, the suitability of water you have now and the water you need for the future depend on its quantity, quality and reliability.

Water stocktake: quantity

Knowing where water is on your property and how much you have available is vital in times of drought. Assessing your water resources involves:

• Personal knowledge of your property
• Continuous observation
• Knowing the quantity of each water storage
• Knowing the safe pumping rate from bores or wells
• Being aware of any conditions (like cease-to-pump rules) in any water sharing plans for your area
• Monitoring evaporation rates
• Drawing on past experiences of water use during drought and long dry spells, e.g., which water storages are spring fed and which have had extremely poor quality water in the last 10-15% of years.

Your major water storages are critical in times of drought.

What size are your existing dams?

Stock Water Calculation

Width (m) x Length (m) = Surface area (m²) x Depth (m) x 0.4 (slope conversion factor) = Approximate volume (m³) ÷ 1,000 = Water storage capacity (ML) 

Water stocktake: quality

Good quality water is vital for your stock, household and business. It is, therefore, important to identify and correct any water quality problems. Knowing your water quality allows you to plan for water treatments to avoid problems such as poor plant growth, blocked irrigation or stock watering pipes, staining and other undesirable effects.

Problems with water quality may have a chemical basis (e.g., pH or concentrations of certain elements) or they may be due to physical causes (e.g. turbidity when the water is cloudy with suspended solids). Some problems may be more obvious, while other problems may require more extensive analysis and treatment. Some of the common problems that affect water quality are hardness (high in dissolved minerals, largely calcium and magnesium), algae and salinity. Poor water quality can even render water unusable.

After testing, water quality problems can be identified and corrected.

Common problems affecting water quality include pH (best between 6.5–8.5), iron, hardness, corrosion, salinity, other elements, turbidity/cloudiness, algae, colour, taste and odour, bacterial growth.

Water quality testing

If you have any doubt about the quality of water that you use for irrigation, stock or domestic purposes you should get it tested by an accredited laboratory. It is a good idea to have your water tested before, and sometimes during use. Beware salts levels can change seasonally and concentrate in waterways over summer, making them unsuitable for weaners.

If stock show any reluctance to drink, provide an alternative supply if possible, and consider getting your water tested.

Water stocktake: reliability – meeting the water demand

As part of assessing your property’s water sources you will need to consider the average versus peak demand and how well-equipped you are to meet an unexpected interruption to normal water supplies.

Thinking about your property’s water supplies as ‘managing your water budget’ is a good way to begin looking for efficiencies in water use across all your operations. A water budget plan may limit the situation of a forced destock due to insufficient water supplies.

Water requirements and maximum advisable levels of salinity and conductivity vary widely according to the type of stock and the type of grazing.

Water requirements for stock classes

Notes: 

• Water consumption by sheep can increase by 80% in extreme, hot conditions.
• Sheep can drink 40% more in summer than winter, and 50–80% more if their water contains more than than 2,000 ppm total dissolved salts (TDS).
• Water at 4,000–10,000 ppm TDS may cause problems initially until animals adjust.
• Dissolved salts in water are expressed in milligrams per litre (equivalent to parts per million – ppm) or in terms of the electrical conductivity of the water, measured in decisiemens per metre (dS/m) or microsiemens per centimetre (μS/cm). 1 dS/m = 1000 μS/cm = approx. 640 mg/L or 640 ppm)
• Include native animals in your calculations, although sheep drink around 6.5 times more water each day than kangaroos.
• When planning water supply requirements, allow for evaporation losses, e.g. the NSW Southern Tablelands average 25% loss of dam water over the late spring, summer, autumn period.

Remember: your water budget is just as critical as your feed budget.

Example

A water storage dam has a capacity of 1.44 ML. At assessment, the water storage is 60% full. How many sheep could this water storage potentially service over the spring, summer and autumn period without rainfall top up?

This document was prepared with the assistance of Greg Meaker, NSW Department of Primary Industries Livestock Officer Goulburn, and StockPlan^®.