1. Q: What is the minimum pipe size for a water service line in Philadelphia?
ANSWER 3/4 inch for residential, 1 inch minimum for commercial
applications.
2. Q: What code governs plumbing installations in Philadelphia? ANSWER
The Philadelphia Plumbing Code, based on the International Plumbing Code
(IPC) with local amendments.
3. Q: What is the maximum allowable pressure for a residential water system?
ANSWER 80 PSI. Pressure reducing valves required if supply pressure
exceeds this.
4. Q: How often must backflow prevention devices be tested? ANSWER
Annually by a certified backflow prevention device tester.
5. Q: What is the minimum size for a building drain serving a single-family
dwelling? ANSWER 3 inches in diameter.
6. Q: What is required when a plumbing permit is pulled in Philadelphia?
ANSWER Licensed master plumber supervision, approved plans, proper
inspections, and permit fees.
7. Q: What is the maximum fixture unit load for a 3-inch building drain?
ANSWER 35 fixture units at 1% grade, 42 fixture units at 2% grade.
8. Q: What type of joints are prohibited in DWV systems? ANSWER
Running threads, saddle joints, and band clamps on the hub.
9. Q: What is the minimum trap seal depth required? ANSWER 2 inches
minimum, 4 inches maximum.
10. Q: How far can a fixture be from its trap? ANSWER Maximum 24 inches
horizontal distance from trap weir to fixture outlet.
,11. Q: What is the minimum slope for a 4-inch building sewer? ANSWER 1%
grade (1/8 inch per foot).
12. Q: What materials are approved for water service lines in Philadelphia?
ANSWER Copper (Type K), PEX, CPVC, and approved plastic materials.
13. Q: What is the required air gap for a dishwasher drain? ANSWER
Minimum 1 inch above the flood level rim of the sink or disposal.
14. Q: What is the maximum length of a fixture drain? ANSWER Depends on
pipe size: 1.25" = 2.5 feet, 1.5" = 3.5 feet, 2" = 5 feet.
15. Q: What size vent is required for a water closet? ANSWER Minimum 3
inches in diameter.
16. Q: What is the minimum clearance required in front of a water closet?
ANSWER 21 inches minimum, 24 inches preferred.
17. Q: What type of valve is required for water heater installation? ANSWER
Full port ball valve or gate valve on cold water inlet.
18. Q: What is the maximum temperature for hot water at fixtures? ANSWER
120°F for residential, 110°F for commercial lavatories.
19. Q: How many fixture units does a standard residential toilet represent?
ANSWER 4 fixture units for drainage, 2.5 fixture units for water supply.
20. Q: What is required for underground drainage piping joints? ANSWER
Joints must be watertight and root-resistant.
21. Q: What is the minimum diameter for a stack vent? ANSWER Must be at
least half the diameter of the drain it serves, minimum 1.25 inches.
22. Q: What materials cannot be used for potable water piping? ANSWER
Lead pipes, galvanized steel in new construction, and non-approved plastics.
23. Q: What is the maximum spacing for pipe hangers on horizontal copper
tubing? ANSWER 6 feet for sizes up to 1.25", 8 feet for sizes 1.5" and larger.
24. Q: What protection is required for water piping in exterior walls?
ANSWER Insulation and protection from freezing temperatures.
25. Q: What is the minimum working pressure for pressure testing water
systems? ANSWER 150 PSI or 50 PSI above working pressure, whichever is
greater.
, 26. Q: What is required when connecting to the public sewer? ANSWER
Permit from Philadelphia Water Department and licensed contractor
installation.
27. Q: What is the minimum height for a shower head? ANSWER 72 inches
above the shower floor.
28. Q: What type of fitting is prohibited for direction changes in DWV
systems? ANSWER Square head plugs, tapped tees, and 90-degree elbows in
horizontal runs.
29. Q: What is the maximum developed length for a building drain? ANSWER
No specific limit, but must maintain proper slope and cleanout access.
30. Q: What is required for water heater venting? ANSWER Proper draft
hood, adequate combustion air, and approved venting materials.
31. Q: What is the minimum pipe size for a washing machine drain?
ANSWER 2 inches in diameter.
32. Q: What is required for cross-connection control? ANSWER Backflow
prevention devices appropriate to the hazard level.
33. Q: What is the maximum fixture unit load for a 1.5-inch trap arm?
ANSWER 3 fixture units.
34. Q: What materials are approved for building sewers in Philadelphia?
ANSWER Cast iron, PVC, concrete, and other approved materials for specific
applications.
35. Q: What is the minimum clearance around a water heater? ANSWER 6
inches on sides, 18 inches in front for service access.
36. Q: What is required for fixture supply stops? ANSWER Individual stops
for each fixture, accessible for maintenance.
37. Q: What is the maximum pressure drop allowed in a water distribution
system? ANSWER System should maintain adequate pressure at furthest
fixture.
38. Q: What type of trap is required for floor drains? ANSWER Deep seal
trap with cleanout and primer connection where required.
39. Q: What is the minimum size for a laundry tub drain? ANSWER 1.5
inches in diameter.
ANSWER 3/4 inch for residential, 1 inch minimum for commercial
applications.
2. Q: What code governs plumbing installations in Philadelphia? ANSWER
The Philadelphia Plumbing Code, based on the International Plumbing Code
(IPC) with local amendments.
3. Q: What is the maximum allowable pressure for a residential water system?
ANSWER 80 PSI. Pressure reducing valves required if supply pressure
exceeds this.
4. Q: How often must backflow prevention devices be tested? ANSWER
Annually by a certified backflow prevention device tester.
5. Q: What is the minimum size for a building drain serving a single-family
dwelling? ANSWER 3 inches in diameter.
6. Q: What is required when a plumbing permit is pulled in Philadelphia?
ANSWER Licensed master plumber supervision, approved plans, proper
inspections, and permit fees.
7. Q: What is the maximum fixture unit load for a 3-inch building drain?
ANSWER 35 fixture units at 1% grade, 42 fixture units at 2% grade.
8. Q: What type of joints are prohibited in DWV systems? ANSWER
Running threads, saddle joints, and band clamps on the hub.
9. Q: What is the minimum trap seal depth required? ANSWER 2 inches
minimum, 4 inches maximum.
10. Q: How far can a fixture be from its trap? ANSWER Maximum 24 inches
horizontal distance from trap weir to fixture outlet.
,11. Q: What is the minimum slope for a 4-inch building sewer? ANSWER 1%
grade (1/8 inch per foot).
12. Q: What materials are approved for water service lines in Philadelphia?
ANSWER Copper (Type K), PEX, CPVC, and approved plastic materials.
13. Q: What is the required air gap for a dishwasher drain? ANSWER
Minimum 1 inch above the flood level rim of the sink or disposal.
14. Q: What is the maximum length of a fixture drain? ANSWER Depends on
pipe size: 1.25" = 2.5 feet, 1.5" = 3.5 feet, 2" = 5 feet.
15. Q: What size vent is required for a water closet? ANSWER Minimum 3
inches in diameter.
16. Q: What is the minimum clearance required in front of a water closet?
ANSWER 21 inches minimum, 24 inches preferred.
17. Q: What type of valve is required for water heater installation? ANSWER
Full port ball valve or gate valve on cold water inlet.
18. Q: What is the maximum temperature for hot water at fixtures? ANSWER
120°F for residential, 110°F for commercial lavatories.
19. Q: How many fixture units does a standard residential toilet represent?
ANSWER 4 fixture units for drainage, 2.5 fixture units for water supply.
20. Q: What is required for underground drainage piping joints? ANSWER
Joints must be watertight and root-resistant.
21. Q: What is the minimum diameter for a stack vent? ANSWER Must be at
least half the diameter of the drain it serves, minimum 1.25 inches.
22. Q: What materials cannot be used for potable water piping? ANSWER
Lead pipes, galvanized steel in new construction, and non-approved plastics.
23. Q: What is the maximum spacing for pipe hangers on horizontal copper
tubing? ANSWER 6 feet for sizes up to 1.25", 8 feet for sizes 1.5" and larger.
24. Q: What protection is required for water piping in exterior walls?
ANSWER Insulation and protection from freezing temperatures.
25. Q: What is the minimum working pressure for pressure testing water
systems? ANSWER 150 PSI or 50 PSI above working pressure, whichever is
greater.
, 26. Q: What is required when connecting to the public sewer? ANSWER
Permit from Philadelphia Water Department and licensed contractor
installation.
27. Q: What is the minimum height for a shower head? ANSWER 72 inches
above the shower floor.
28. Q: What type of fitting is prohibited for direction changes in DWV
systems? ANSWER Square head plugs, tapped tees, and 90-degree elbows in
horizontal runs.
29. Q: What is the maximum developed length for a building drain? ANSWER
No specific limit, but must maintain proper slope and cleanout access.
30. Q: What is required for water heater venting? ANSWER Proper draft
hood, adequate combustion air, and approved venting materials.
31. Q: What is the minimum pipe size for a washing machine drain?
ANSWER 2 inches in diameter.
32. Q: What is required for cross-connection control? ANSWER Backflow
prevention devices appropriate to the hazard level.
33. Q: What is the maximum fixture unit load for a 1.5-inch trap arm?
ANSWER 3 fixture units.
34. Q: What materials are approved for building sewers in Philadelphia?
ANSWER Cast iron, PVC, concrete, and other approved materials for specific
applications.
35. Q: What is the minimum clearance around a water heater? ANSWER 6
inches on sides, 18 inches in front for service access.
36. Q: What is required for fixture supply stops? ANSWER Individual stops
for each fixture, accessible for maintenance.
37. Q: What is the maximum pressure drop allowed in a water distribution
system? ANSWER System should maintain adequate pressure at furthest
fixture.
38. Q: What type of trap is required for floor drains? ANSWER Deep seal
trap with cleanout and primer connection where required.
39. Q: What is the minimum size for a laundry tub drain? ANSWER 1.5
inches in diameter.
