# TPR and Drainage pipes **URL:** \ **Category:** Inspection Education & Training\ **Created:** [August 6, 2026, 12:33am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691 "2026-08-06T00:33:07Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![ncroley](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ncroley/32/422277_2.png) [@ncroley](https://forum.nachi.org/u/ncroley)\ **Post date:** [August 6, 2026, 12:33am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/1 "2026-08-06T00:33:07Z")
I am under the impression that a TPR valves drainage pipe should not terminate into the water heater catch pan. Im not sure what I would say in regards to this in a report. ---
**Author:** ![ruecker](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ruecker/32/357170_2.png) [@ruecker](https://forum.nachi.org/u/ruecker)\ **Post date:** [August 6, 2026, 1:09am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/2 "2026-08-06T01:09:50Z")
> [@ncroley](#): > > I am under the impression that a TPR valves drainage pipe should not terminate into the water heater catch pan. Im not sure what I would say in regards to this in a report… You could just say… > [@ncroley](#): > > TPR valves drainage pipe should not terminate into the water heater catch pan… I think the issue is that the catch pan drainage may not be able to keep up with the potential discharge rate from the TPR valve. With that in mind, I would review the circumstances of the installation before making a big deal about it. As an example, many water heaters are installed in unfinished basements in my area. Many times there is a floor drain a few feet from the water heater. If someone happened to put a pan under the water heater for whatever reason, I’m not going to care much if the TPR valve discharges into it in that scenario. But if the water heater is installed on the main floor or upper level and there is a chance that a pan overflow would cause damage, it becomes a bigger concern. ---
**Author:** ![ncroley](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ncroley/32/422277_2.png) [@ncroley](https://forum.nachi.org/u/ncroley)\ **Post date:** [August 6, 2026, 1:32am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/3 "2026-08-06T01:32:34Z")
Thanks Ryan. Mine is located in the garage on a raised platform ---
**Author:** ![bhull1](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bhull1/32/180000_2.png) [@bhull1](https://forum.nachi.org/u/bhull1)\ **Post date:** [August 6, 2026, 1:36am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/4 "2026-08-06T01:36:03Z")
![Water Heater](https://global.discourse-cdn.com/internachi/original/4X/b/3/2/b327cd13efec7871390a628851d6eab063dae0e6.jpeg) I disagree. I actually like to see the TPRV pipe directed into (within 6" of) a catch pan under the water heater but that is not the only way to do it. Here are actual requirements for the TPRV drain pipe. Read and remember these so you don’t call something out a as defect when it is actually just fine. 1. **Not directly connected** to the drainage system. 2. **Must discharge through an air gap** located in the same room as the water heater. 3. **Must not be smaller** than the diameter of the valve outlet and must remain full size all the way to the termination (no reductions). 4. **Must serve only one** relief device (cannot be shared with another TPRV or other equipment). 5. **Must discharge** to the floor, the water heater pan, a waste receptor, or the outdoors. 6. **Must not cause personal injury or structural damage** when it discharges. 7. **Termination point must be readily observable** by the building occupants. 8. **Must not be trapped** (no low spots that hold water). 9. **Must flow by gravity** (continuous downward slope, no uphill sections). 10. **Must terminate** not more than 6 inches above the floor or waste receptor, and not less than two times the pipe diameter above the floor/flood-level rim. 11. **No threaded connection** at the end of the pipe. 12. **No valves or tee fittings** anywhere on the discharge pipe. 13. **Must be made of approved materials** (copper, CPVC, galvanized steel, PEX/PE-RT that is rated for the temperature, etc.). PVC is **not** allowed. 14. (When insert fittings are used) The pipe must be **one nominal size larger** than the valve outlet. (for further reading, this list is based on IRC Section P2804.6.1) ---
**Author:** ![ncroley](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ncroley/32/422277_2.png) [@ncroley](https://forum.nachi.org/u/ncroley)\ **Post date:** [August 6, 2026, 1:47am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/5 "2026-08-06T01:47:43Z")
Thanks for referencing the code because the plumbing course says its not an indirect waste receptor so it is not permitted, definitely had me unsure. ---
**Author:** ![ruecker](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ruecker/32/357170_2.png) [@ruecker](https://forum.nachi.org/u/ruecker)\ **Post date:** [August 6, 2026, 2:16am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/6 "2026-08-06T02:16:21Z")
> [@bhull1](#): > > Read and remember these so you don’t call something out a as defect when it is actually just fine… I would just add, if the OP is going to use the code (swear word, lol) as their reference point, they should be sure to check their actual code in effect in their area. In my state, it is not technically allowed to discharge into the pan, but as I stated above, inspectors should use common sense. ![image](https://global.discourse-cdn.com/internachi/original/4X/3/f/b/3fb9b217124ad3e99a447d254a9d7e4dbe7dc663.png) ---
**Author:** ![ruecker](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/ruecker/32/357170_2.png) [@ruecker](https://forum.nachi.org/u/ruecker)\ **Post date:** [August 6, 2026, 2:19am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/7 "2026-08-06T02:19:48Z")
> [@ncroley](#): > > Thanks for referencing the code… As I stated in the post above, what one inspector references as code in their area, may not apply to the code in your area. If you are going to use the code as your reference for calling things out, you have to make sure you know what the code is in your area. ---
**Author:** ![bhull1](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bhull1/32/180000_2.png) [@bhull1](https://forum.nachi.org/u/bhull1)\ **Post date:** [August 6, 2026, 2:38am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/8 "2026-08-06T02:38:57Z")
### Comparison | Code | Section | Can TPRV discharge into the water heater pan? | | --- | --- | --- | | **IRC** | P2804.6.1 | **Yes** – explicitly allowed (“to the pan serving the water heater”) | | **IPC** | 504.6 | **Yes** – same language | | **UPC** | 608.5 | **No** – specifically prohibited | Most of the Eastern U.S. adopts the International codes (IRC/IPC), not the UPC. The UPC is primarily used in Western states . But local jurisdictions can differ from one area to the next, so Ryan is right about not referencing code, to stay out of arguments or other trouble. And I’ll repeat, don’t call something out a as defect when it is actually just fine. ---
**Author:** ![mgoldenberg](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mgoldenberg/32/89265_2.png) [@mgoldenberg](https://forum.nachi.org/u/mgoldenberg)\ **Post date:** [August 6, 2026, 2:49am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/9 "2026-08-06T02:49:14Z")
> [@bhull1](#): > > Most of the Eastern U.S. adopts the International codes (IRC/IPC) Just like Florida, that brought it to the FL Bldg Code ---
**Author:** ![bcawhern1](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/bcawhern1/32/408713_2.png) [@bcawhern1](https://forum.nachi.org/u/bcawhern1)\ **Post date:** [August 6, 2026, 3:08am UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/10 "2026-08-06T03:08:18Z")
> [@bhull1](#): > > don’t call something out a as defect when it is actually just fine. I agree. I think calling that out is nothing more than a gotcha moment and will save zero lives. However, if I observe other install problems, it may make an honorary mention in my defect narrative. ---
**Author:** ![rkenney](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rkenney/32/405447_2.png) [@rkenney](https://forum.nachi.org/u/rkenney)\ **Post date:** [August 6, 2026, 1:07pm UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/11 "2026-08-06T13:07:10Z")
> [@bhull1](#): > > I disagree. What Nathan presented is exactly how my county now does it. They require a drip pan (mine has one). In my case there is no floor drain so the drip pan drain goes nowhere (it is capped off). The TPR drain pipe makes 2 - 90° bends to clear the drain pan. Installation was inspected by the local AHJ (as required for gas WH). ![TPR2](https://global.discourse-cdn.com/internachi/original/4X/b/2/3/b237d32bcb3699007c325338002235b049f36f53.jpeg) Should you have a leak this installation will quickly tell you if it is TPR (pressure / temperature) or the WH tank. The only TPRs I ever call out are ones with NO discharge line or one that is severely restricted. ![TPR](https://global.discourse-cdn.com/internachi/original/3X/9/9/99b289b665319f198148f9fa8f4724078545e675.jpeg) ---
**Author:** ![rthornburg](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/rthornburg/32/60113_2.png) [@rthornburg](https://forum.nachi.org/u/rthornburg)\ **Post date:** [August 6, 2026, 5:08pm UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/12 "2026-08-06T17:08:47Z")
> [@ncroley](#): > > TPR valves drainage pipe should not terminate into the water heater catch pan. The IRC allows it but the UPC doesn’t. It’s a good idea to take it outside because the issue with using the pan is if it starts dripping it might drip for a long time before someone notices it and rust out the bottom of the water heater. When this happens you can’t just replace the TPR valve because the argument can be made that the tank was leaking. The client will want a new water heater. So a cheap repair is now an expensive repair. ---
**Author:** ![imayer](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/imayer/32/197054_2.png) [@imayer](https://forum.nachi.org/u/imayer)\ **Post date:** [August 6, 2026, 6:30pm UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/13 "2026-08-06T18:30:15Z")
It’s specifically not allowed under the California plumbing code. If that applies to other states or not, I don’t know. ---
**Author:** ![mwilles](https://sea2.discourse-cdn.com/internachi/user_avatar/forum.nachi.org/mwilles/32/181480_2.png) [@mwilles](https://forum.nachi.org/u/mwilles)\ **Post date:** [August 6, 2026, 8:39pm UTC](https://forum.nachi.org/t/tpr-and-drainage-pipes/269691/14 "2026-08-06T20:39:05Z")
> [@ncroley](#): > > I am under the impression that a TPR valves drainage pipe should not terminate into the water heater catch pan. Your impression is not correct if your jurisdiction follows the IRC. The majority of the country does.