Water is the most important substance on the Earth for living creatures

Those of us interested in the prospect of life existing outside our planet are well aware that scientists assume that a remote planet MUST have (or have had) water on it to support life-forms. 

Mammalian bodies consist of 70% + water, and most of this is intracellular. Animals (including humans) can survive the loss of most of their stored carbohydrate (as glycogen),  most of their stored fat (as adipose tissue), and over 50% loss of body protein - but if they lose just 10% of body water they are seriously ill, and loss of 15% water can lead to death !

Owners must therefore ensure that their pets are provided with sufficient fresh, clean water and water should be available 24 hours a day, 365 days a year. 

Water can be a source of infection for animals, so dirty, soiled water should be removed from the environment as soon as possible, and the supply replenished.

Human grade tap water is ideal for most pets and it should contain less than 5000ppm  total dissolved solids (TDS). Water containing over 7000ppm total TDS is considered unacceptable for livestock and other animals . Salt water living creatures require highly specific water conditions. Hard water contains high concentrations of mineral components eg calcium, magnesium and other anions. Commercial mineral water packaged for human consumption should not be given to pets, except on the advice of a veterinarian, because some are very high in salt, calcium, magnesium and other minerals which could be contraindicated for your pet. For example, pets with hypertension or struvite urolithiasis should not be given water with high sodium or magnesium concentrations, respectively. 

Water should not be provided to pets if it could be :

• Contaminated with insecticides or other agrochemicals
• Contaminated with industrial chemicals eg mineral oils, petrol,  etc
• Stagnant
• Contaminated with sewage (human or animal in origin)
• Contaminated by rodent urine (a source of leptospirosis)

How much water do pets need ?

Water requirements depend upon :

• Maintenance requirement
• Additional intake to replace water losses

Water loss from the body increases with :

• Exercise 
• Panting - in high environmental temperatures, disease, or exercise
• Sweating - in high environmental temperatures, disease, or exercise
• Increased urinary losses - diuresis
• Vomiting
• Excessive salivation (hypersalivation or ptyalism)
• Increased faecal losses - diarrhoea
• Metabolic waste
• Lactation
• Haemorrhage
• High body temperature

There are three main sources of water for pets :

• Water they drink
• Water in food that they eat. Canned pet foods can contain up to 80% water, dry foods up to 10% water, and soft-moist foods contain 25-40% water.
• Water they produce by internal metabolic processes (during the breakdown of protein, fats and carbohydrates to release energy)  About 10-16g of water are produced for every 100kcal of energy produced.

As a general rule dogs and cats require the same amount of water (ml/day) as they do calories (kcal/day) .

Updated October 2013