I work in a smilar environment to yourself at times....
Get this...........
I made a new potable water tank for a project, very nice stainless steel job...... 8000 litre.
So our business made a small prfit on the job, it was a weeks work...customer happy, me happy...
Because it was to be used for drinking water, it to had a sterilisation certificate.........Guy came with a vacuum cleaner and a pump action hand spray, put a bit of peroxide about the place.....1.5 hous plus travelling, and a bit of paperwork. £800 plus vat.
He made more than us ...................I went f'ing m