In most states the public water supply of cities and towns is inspected regularly and the water is examined, so that the people may be protected from danger of infection. When the water used in a household is obtained from a well or private water supply, an analysis of it should be made. All wells should be carefully constructed and covered, so that there may be no danger of pollution from surface drainage. Privy vaults should not be near the well or so located that there will be drainage from them to a well; otherwise the germs of typhoid and other diseases may find their way to it through the ground and become a source of danger to the persons using the water. As an extra precaution all discharges from persons who have tuberculosis, cholera, dysentery, or typhoid fever should be effectively disinfected before they are emptied into a privy vault or into a flush closet. =Purification of water.= If the purity of the water is doubted, it should be boiled for five or ten minutes in a clean, covered kettle. This renders it safe. The flat taste which often results from the boiling may be remedied by shaking the water in a bottle or pouring it from one clean pitcher to another or by simply exposing it to the air overnight. Water should be kept cool, and should be protected from dust. =Household filters.= The domestic filter is of little value. It will remove visible particles of matter, but will have very little effect upon bacteria. If such filters are used, they should be carefully and intelligently cleaned several times a day. =Care and arrangement of rooms.= All the rooms in the house should be well ventilated and kept scrupulously clean. The windows should be entirely screened in order that they may be opened at both top and bottom. The screens should be put on in the spring before the flies and mosquitoes appear and should not be removed until all danger from them is past. Screens should be brushed frequently. =Dust and dusting.= Dust is brought into the home on shoes and clothing, and is blown in from the outside. Dust must be kept under control by the use of a vacuum cleaner, a carpet sweeper, or a damp broom, and by good ventilation. Children should not be allowed to remain in rooms that are being swept, for dust causes an irritation of the eyes, nose, and throat and also is frequently a carrier of disease germs. The dusting of furniture should be done with a damp cloth. This will wipe off the dust and not stir it up into the air where it will be inhaled or will settle again. A feather duster should not be used. Dampened dusters may be prepared in the following way: spread the dusters out smoothly on a towel that has been wrung out of hot water, roll, and let them lie for half an hour before using.