Gray water is water that has been used for some non-sewage purpose. Examples:
Using a fine-mesh sink strainer or similar to remove food particulates reduces the likelihood of unpleasant smell. Straining is particularly important if stealth draining (see below) to avoid unsightliness, reduce visible evidence, and avoid attracting flies and bears.
Gray water is held in different ways depending on the dweller's RV setup:
It is common, though not universally smiled upon, to stealthily drain gray water over grassy areas, drains, etc. The public perception of stealth draining may be far worse than the reality of it, especially if one uses biodegradable soap and strains food particulates from dishwashing water. For safety and neighborliness, follow location guidelines one might use for a cathole toilet.
To increase stealth locate the drain on the camper so you can easily and stealthily release into grass (near back bumper, etc). Drain only at night; not only does this reduce the chance of being spotted but also gives any damp ground a chance to dry up by morning.