All workplaces should provide adequate places for washing at readily accessible places. The type of workplace may make the type of washing facilities differ though. Those working with materials that can get residue on clothes or skin might need showering facilities (among other jobs) so this might be a requirement of a job.
Below is an outline of the number of toilets required in workshops:
1-5 people need 1 toilet
6-25 people need 2 toilets
26-50 people need 3 toilets
51-75 people need 4 toilets
76-100 people need 5 toilets