What are the requirements for above-ground swimming pools?
Complete a building permit application form and submit a check or money order payable to City of Philadelphia for $32. Prior to using the pool, call the L&I District Office in your area to schedule an appointment at your residence with a building inspector. Do not use the pool until its construction has been approved.
A permit is required for all above-ground pools 12 feet or greater in maximum dimension. The pool, accompanying structures, and equipment must not be located in the front or side yard, nor within two feet of any property line or structures on the lot.
The pool may have an access platform of up to 50 square feet included as part of this permit. the required guard rail around the platform must be at least 36" high and may have a maximum opening of 4'.
Pool water must be properly treated and free of scum, debris, and foreign matter. Discharge water must not create a nuisance to an adjoining property. 

More information from L&I
Swimming Pool and Spa Safety 
Thinking of installing a swimming pool for your family and friends to enjoy? Philadelphia’s Department of Licenses and Inspections would like to assist you in making your pool installation as safe as possible. Following a few guidelines and obtaining permits and inspections for these installations will 
help you create a safer installation. 
Conditions 
• The pool must not be located in the front or side yard, and not within two feet of any property line or structure on the lot. 
• Water must be properly treated and free of scum, debris, and foreign matter. Discharge water must not create a nuisance to an adjoining property. 
• The pool must be installed in accordance with the Manufacturer’s Specifications. 
• In-ground pools must be located a minimum distance from all property lines equal to the depth of the pool adjoining such property lines. 
• Suction outlets must be designed to – supervision.  
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