A typical footbath should be 3 metres by 1 metre and 10cm deep and this would contain 300 litres of water. To get a 5% solution of copper sulphate you need 15kg of copper sulphate (25%), but many farms need an 8% solution to control digital dermatitis i.e. 24kg Copper Sulphate. How long does a copper sulphate bath last? One passage of up to 300 cows for a 300 litre footbath, if you have a 150 cow herd and use the solution for 2 milkings its effect will be reduced at the second milking due to the effect of manure in the footbath. How long before the footbath is used should I make up the solution? To get the maximum release of copper ions into the footbath make up the solution at least 4 – 5 hours before use.