Background information on Disposal
In each chemical page, general advice is given for methods of dealing with small quantities of individual chemicals. The following phrases are commonly used.
Wash to waste means dilution with a large volume of water and washing down the foul water drains. The laboratory sink drains almost certainly lead to such drains, but check before using them for disposal. External drains, e.g. those collecting rain water, are normally storm water drains and are not to be used for this purpose.
Place in ordinary refuse means in an ordinary waste bin. Care must be taken to ensure cleaners are not harmed. It will thus sometimes be preferable to place disposals directly in large external bins rather than into the small ones in the laboratory.
Washings means what is left in the container after it has been emptied. i.e. after you have turned your test tube upside down, what is left counts as washings and can in almost all cases be washed to waste.
Small quantities is a bit of a slippery concept. Where a DIY disposal is described, then the amounts mentioned there count as small quantities.
Large quantities of most chemicals and even small quantities of some very toxic ones are best dealt with by a licensed disposal contractor.
See the Disposal section on any Hazards & Remedial Measures pages for advice on disposal of small quantities of heavy metal salts, oxidising agents and solvents.
See the other articles in this section for more comprehensive background info on Disposal.