Broad irrigation is a method which cannot generally be used on account of the large amount of land and labor required. This method is especially applicable to asylums, alms houses, and reformatories where cost of labor is small. It is used in the West where the value of all available water leads to the application of sewage to crops, and also on account of the low stage of western streams during the summer which renders sewage discharged into them an unbearable nuisance. Intermittent downward filtration may be used where there is a considerable area of sandy soil, and also where a high degree of purification is necessary. Chemical precipitation does not require a large area for its operation and used alone does not give a high degree of purification. Where land and material for beds is expensive, and partial purification is sufficient, this system may be used. The septic tank requires a small area. The odors are not offensive and cannot be noticed 100 feet away. The effluent may be discharged into small streams and soon loses its identity. Contact beds are used where a high degree of purity is required; if the effluent is emptied into rivers or sources of water supply. The beds do not require a large area and the process may be recommended if suitable material is at hand. The cost of construction and maintenance of the different systems vary so largely according to local conditions that a fair estimate is not possible. As the most striking example of maximum and minimum cost the disposal system at Chicago and at Lowell, Massachusetts may be cited. The purification in both cases is by dilution, the cost being practically nothing at Lowell while the Chicago Drainage Canal cost $33,000,000. It may not be fair to charge this entire cost to the sewerage system; nevertheless up to date it has been used for no other purpose. At Berlin, Germany where broad irrigation is used, the sewage has to be pumped to the farms and involves a considerable cost. Aside from this the receipts derived from the sale of farm products are enough to pay the running expenses of the farm. The first cost of the intermittent downward filtration plant is estimated by the writers at $90,000 per million gallons per day of sewage treated, where the beds are artificial. Where natural beds can be used the first cost may be reduced to $7,500 per million gallons per day. The cost of maintenance is about $2.00 per 1,000,000 gallons. The average cost for operating a chemical disposal plant is about 58 cents per inhabitant per year, or $16.00 per 1,000,000 gallons treated. At Manchester England where broad irrigation and chemical precipitation are used in combination, the average cost was $63.00 per 1,000,000 gallons treated. A septic tank for treating 1,000,000 gallons of sewage per day will cost less than $10,000 and the cost of maintenance will be about $1.00 per 1,000,000 gallons treated. _Conclusion_