Bleach is an extremely effective cleaning and disinfecting agent. Although you can buy it very cheaply at the store (around $1/gallon), if you are really frugal (or just interested in chemistry) it can be made quite easily. Make sure you perform this experiment outside or in a well-ventilated room with no smoking, because flammable hydrogen gas is evolved.
Cooking pot (should be as large as possible)
Two iron nails
Computer power supply or automotive battery charger.
Postal Scale for Weighing Powder
The first step is to get the pot and fill it with water. Then get some salt, and add it to the water until the water can hold no more. Then connect a nail, using wire, to a terminal of the battery charger or power supply. Do the same for the other nail and terminal. If you are using a computer power supply, remember that the connector with a colored wire is one terminal and the connector directly next to it (usually it has a black wire) is another. Even though there are four connectors, you will only be using those two. Drop the connected nails into the pot with salt water. Turn on the battery charger or power supply. You should soon see tiny bubbles in the bucket. If you don't, something is wrong. Try to stay away from the bucket; it can evolve flammable and poisonous gas. The temperature of the water should never exceed 90 deg. F. Make sure to put some ice around the bucket to cool the water.
Leave the bucket alone for a day, then turn off the power supply, and the nails. Put the pot on the stove at full power and heat the pot. After a considerable amount of the water has boiled, you should start seeing a powder accumulate at the bottom of the pot. When it appears that no more powder is accumlating, turn off the stove. Wait for the water to cool down, then pour everything into the other bucket, making sure that it is through the coffee filter. The filter will catch the powder, and let the "depleted" salt water flow through into the bucket. If the filter gets full, empty it out in a separate container (not the pot), and continue pouring. When you are finished, pour the water in the bucket back into the pot. To make the bleach, put tap water in the bucket you just emptied, and add the powder to it, making sure that the ratio is 200 grams of powder for every gallon of tap water.
The water in the pot still has some salt in it; therefore it can be used toward the salt requirement for the next batch.