Hydration guidance

The general guidance we currently provide regarding volumes, was originally developed for wearing BA in the fire training unit, hence the references to working in hot environments and performance in the heat. Obviously the guidance is relevant to working in hot operational environments or at high rates of extended periods (e.g. Grass Fires), but it is difficult to know when this is going to happen, unlike in training. So while it is important to be well hydrated on station, in preparation for calls, the guidance really is aimed at extended physical work and / or work in heat and would probably be excessive all day with such exertion.

Why must drinking guidelines be general ?

The problem with providing drinking guidelines is that they must be general, as people sweat at different rates for the same tasks, will carry out different tasks on the fire ground, produce different amounts of salt on their sweat, have different body sizes (therefore fluid volume), begin a shift at different states of hydration etc, and therefore will need to drink different amounts to keep well-hydrated.

Why is drinking too much water a problem ?

Over drinking (hyponatremia: hypo - denoting a deficiency or abnormally low level, natremia - pertaining to sodium) it is quite unusual, but can happen, and has recently been an issue for marathon runners.

When a person is sweating profusely for extended periods of time, drinking too much water becomes a problem because the body is losing water and salt in the sweat, but only the water is being replaced. This dilutes the electrolyte (salt) content of the plasma (the liquid part of your blood), and the imbalance, or lack of salt, can interfere with brain, heart and muscle function.
In extreme circumstances, this can lead to things such as swelling of the brain and water in the lungs, which may result in death. However, in less extreme circumstances, the effects are less severe.

Guidance on avoiding over-drinking.

When exercising for less than an hour, water will read more