Be them eggs bound for consumption or for incubation and hatching; egg washing is an important part of the poultry rearing process. If eggs are left unwashed, bacteria can work its way through the pours of the shell in to the egg and lead to food poisoning in humans and diseases and death in birds incubated in dirty eggs. There are a few ways of handling the problem of dirty eggs.
Before the egg is even laid; there are steps that you can take to lessen the amount of egg washing required to make eggs safe. The use of nest boxes is the best initial way to help prevent eggs getting dirty by being laid on the ground in amongst filth and whatever else. These can easily installed in their pen, near the coop, and are there for the sole purpose of laying. They should be implemented during a flock's early days so that they are more likely to take up the good habit of laying there. Placing nest eggs in there can also help encourage your hens to choose this spot over the ground or the coop. Fill the nest box with comfy bedding to make it a pleasant place to lay and to reduce the chances of breakages.
When it comes to egg washing as a smallholder (we'll define this here as someone with a couple of dozen chickens. Any more and you'll have your work cut out for you), a simple set up of a basin, warm water and some egg washing detergent will suffice. It's important to use a product specifically for the egg washing as eggs are very susceptible to taking on the flavours of the liquid it's washed in. When washing eggs by hand, be sure the temperature of the water is hot but not hot enough to boil and that the eggs are not left in for any longer than 30 seconds. This should give the egg enough time to expand a little and "push" any bacteria out of it's pours. Be sure the temperature of the water doesn't exceed 40°C as you don't want to even come close to cooking the egg(s). Be thorough yet gentle and be sure to change the water between washes.
When it comes to larger flocks, you'll need something a bit more practical than a basin. The Supawash range of egg washers can really speed up the process. Simply collect the eggs with or fill the rubberized basket supplied with up to either 100 or 200 eggs (depending on the model you're using). Plug the egg washer bucket in and fill it with cold water and egg washing detergent (as per their instructions). For liquid egg washing detergent; the usual ratio is 1 part egg wash to 100 parts water. Once filled, allow the washer to heat up to the pre-determined level which is roughly around body temperature. When it reaches temperature, place the egg washer bucket onto the base and ensure it sits securely. Place the basket into the bucket and turn the base on. The movement produced by the base will gently clean the eggs; check this process every couple of minutes and remove the basket once the eggs are clean.