Water Pipe Sizing Chart — Meter & Supply Size from WSFU

The UPC's complete fixture-unit table for determining water pipe and meter sizes: maximum WSFU for each meter and building-supply pairing at every developed length, in all three pressure ranges, per UPC Table 610.4 (2021 edition). The IPC takes the other road — engineered sizing per 604.3 with fixed per-fixture minimums per Table 604.5 (2021 edition) — so the two code families are presented separately and never blended.

UPC — available pressure 30 to 45 psi

UPC Table 610.4

Maximum WSFU served by each water meter and building supply/branch pairing, by maximum developed length in feet, where the available static pressure after head loss is 30 to 45 psi, values per UPC Table 610.4 (2021 edition). The 1/2" row is for branches only — a building supply is never smaller than 3/4".
Meter × supply	40 ft	60 ft	80 ft	100 ft	150 ft	200 ft	250 ft	300 ft	400 ft	500 ft	600 ft	700 ft	800 ft	900 ft	1000 ft
3/4" × 1/2" ‡	6	5	4	3	2	1	1	1	0	0	0	0	0	0	0
3/4" × 3/4"	16	16	14	12	9	6	5	5	4	4	3	2	2	2	1
3/4" × 1"	29	25	23	21	17	15	13	12	10	8	6	6	6	6	6
1" × 1"	36	31	27	25	20	17	15	13	12	10	8	6	6	6	6
3/4" × 1-1/4"	36	33	31	28	24	23	21	19	17	16	13	12	12	11	11
1" × 1-1/4"	54	47	42	38	32	28	25	23	19	17	14	12	12	11	11
1-1/2" × 1-1/4"	78	68	57	48	38	32	28	25	21	18	15	12	12	11	11
1" × 1-1/2"	85	84	79	65	56	48	43	38	32	28	26	22	21	20	20
1-1/2" × 1-1/2"	150	124	105	91	70	57	49	45	36	31	26	23	21	20	20
2" × 1-1/2"	151	129	129	110	80	64	53	46	38	32	27	23	21	20	20
1" × 2"	85	85	85	85	85	85	82	80	66	61	57	52	49	46	43
1-1/2" × 2"	220	205	190	176	155	138	127	120	104	85	70	61	57	54	51
2" × 2"	370	327	292	265	217	185	164	147	124	96	70	61	57	54	51
2" × 2-1/2"	445	418	390	370	330	300	280	265	240	220	198	175	158	143	133

UPC — available pressure 46 to 60 psi

UPC Table 610.4

Maximum WSFU served by each water meter and building supply/branch pairing, by maximum developed length in feet, where the available static pressure after head loss is 46 to 60 psi, values per UPC Table 610.4 (2021 edition). The 1/2" row is for branches only — a building supply is never smaller than 3/4".
Meter × supply	40 ft	60 ft	80 ft	100 ft	150 ft	200 ft	250 ft	300 ft	400 ft	500 ft	600 ft	700 ft	800 ft	900 ft	1000 ft
3/4" × 1/2" ‡	7	7	6	5	4	3	2	2	1	1	1	0	0	0	0
3/4" × 3/4"	20	20	19	17	14	11	9	8	6	5	4	4	3	3	3
3/4" × 1"	39	39	36	33	28	23	21	19	17	14	12	10	9	8	8
1" × 1"	39	39	39	36	30	25	23	20	18	15	12	10	9	8	8
3/4" × 1-1/4"	39	39	39	39	39	39	34	32	27	25	22	19	19	17	16
1" × 1-1/4"	78	78	76	67	52	44	39	36	30	27	24	20	19	17	16
1-1/2" × 1-1/4"	78	78	78	78	66	52	44	39	33	29	24	20	19	17	16
1" × 1-1/2"	85	85	85	85	85	85	80	67	55	49	41	37	34	32	30
1-1/2" × 1-1/2"	151	151	151	151	128	105	90	78	62	52	42	38	35	32	30
2" × 1-1/2"	151	151	151	151	150	117	98	84	67	55	42	38	35	32	30
1" × 2"	85	85	85	85	85	85	85	85	85	85	85	85	85	83	80
1-1/2" × 2"	370	370	340	318	272	240	220	198	170	150	135	123	110	102	94
2" × 2"	370	370	370	370	368	318	280	250	205	165	142	123	110	102	94
2" × 2-1/2"	654	640	610	580	535	500	470	440	400	365	335	315	285	267	250

UPC — available pressure Over 60 psi

UPC Table 610.4

Maximum WSFU served by each water meter and building supply/branch pairing, by maximum developed length in feet, where the available static pressure after head loss is over 60 psi, values per UPC Table 610.4 (2021 edition). The 1/2" row is for branches only — a building supply is never smaller than 3/4".
Meter × supply	40 ft	60 ft	80 ft	100 ft	150 ft	200 ft	250 ft	300 ft	400 ft	500 ft	600 ft	700 ft	800 ft	900 ft	1000 ft
3/4" × 1/2" ‡	7	7	7	6	5	4	3	3	2	1	1	1	1	1	0
3/4" × 3/4"	20	20	20	20	17	13	11	10	8	7	6	6	5	4	4
3/4" × 1"	39	39	39	39	35	30	27	24	21	17	14	13	12	12	11
1" × 1"	39	39	39	39	38	32	29	26	22	18	14	13	12	12	11
3/4" × 1-1/4"	39	39	39	39	39	39	39	39	34	28	26	25	23	22	21
1" × 1-1/4"	78	78	78	78	74	62	53	47	39	31	26	25	23	22	21
1-1/2" × 1-1/4"	78	78	78	78	78	74	65	54	43	34	26	25	23	22	21
1" × 1-1/2"	85	85	85	85	85	85	85	85	81	64	51	48	46	43	40
1-1/2" × 1-1/2"	151	151	151	151	151	151	130	113	88	73	51	51	46	43	40
2" × 1-1/2"	151	151	151	151	151	151	142	122	98	82	64	51	46	43	40
1" × 2"	85	85	85	85	85	85	85	85	85	85	85	85	85	85	85
1-1/2" × 2"	370	370	370	370	360	335	305	282	244	212	187	172	153	141	129
2" × 2"	370	370	370	370	370	370	370	340	288	245	204	172	153	141	129
2" × 2-1/2"	654	654	654	654	654	650	610	570	510	460	430	404	380	356	329

‡ A building supply pipe is never smaller than 3/4" — the 1/2" row applies to branches only. The pressure ranges are the available static pressure after head losses — where the street-main pressure fluctuates, design to the minimum.

IPC — minimum fixture water supply pipe sizes

IPC Table 604.5

The smallest pipe the IPC permits to serve each fixture, whatever the engineered design would otherwise allow, values per IPC Table 604.5 (2021 edition; unchanged 2015–2024).
Fixture	Min supply	Note
Bathtub, 60" × 32" and smaller	1/2"	a
Bathtub, larger than 60" × 32"	1/2"	a
Bidet	3/8"	—
Combination sink and tray	1/2"	—
Dishwasher, domestic	1/2"	a
Drinking fountain	3/8"	—
Hose bibb	1/2"	—
Kitchen sink	1/2"	a
Laundry, 1, 2 or 3 compartments	1/2"	a
Lavatory	3/8"	—
Shower, single head	1/2"	a
Sink, flushing rim	3/4"	—
Sink, service	1/2"	—
Urinal, flush tank	1/2"	—
Urinal, flushometer valve	3/4"	—
Wall hydrant	1/2"	—
Water closet, flush tank	3/8"	—
Water closet, flushometer tank	3/8"	—
Water closet, flushometer valve	1"	—
Water closet, one piece	1/2"	a

a — In a parallel (manifold) distribution system with a developed length of 50 feet or less and at least 35 psi at the meter, the individual line to this fixture may be one nominal size smaller. The fixture supply may not terminate more than 30 inches from the fixture it serves, and reduced-size flexible connectors must be approved for the use (IPC 604.5).

How to use the UPC table

Five inputs drive the lookup (UPC 610.7): the WSFU total from Table 610.3 — on the WSFU chart — the developed length from meter to the most remote outlet, the elevation of the highest outlet above the meter, the street-main pressure, and its minimum where it fluctuates. Deduct the code's elevation allowance for every foot of rise (UPC 610.8), pick the pressure block that matches what's left, find the first length column at or beyond your developed length, and read down to the first row whose WSFU covers the demand — the two left cells are your meter and supply sizes. Copper systems also respect the velocity ceilings of UPC 610.12 (8 ft/s cold, 5 ft/s hot).

Flushometer-valve systems don't total WSFU this way — the UPC sizes those under 610.10. Systems beyond the table's range size by the engineered method (UPC Appendix A). The pipe sizing calculator and pressure loss calculator handle the computed cases.

The IPC path: engineered sizing, fixed minimums

The IPC prints no WSFU-to-pipe-size lookup in its body. Distribution piping must be designed so every fixture receives its minimum flow rate and pressure under peak demand (IPC 604.3), by an approved engineering method (604.1). Where a jurisdiction adopts Appendix E, its segmented-loss procedure does the work: total WSFU per Table E103.3(2), convert to GPM with the demand table, then check pressure losses segment by segment against the appendix's friction figures. Appendices apply only where specifically adopted (IPC 101.2.1). What always applies is Table 604.5 above — no fixture supply drops below its listed minimum. Note the fork against the UPC: the IPC allows 3/8" supplies to lavatories, bidets, and tank water closets where the UPC's Table 610.3 branch minimum is 1/2".

Editions and amendments

UPC Table 610.4 is stable ground — the 2015 and 2021 prints are cell-identical — and this page states the 2021 edition. The 2024 cycle's change in this area is procedural, not tabular: downstream of a pressure regulator, sizing pressure is taken as 80% of the regulator setting. IPC Table 604.5 is unchanged 2015–2024. Cities and states amend water-sizing rules more than almost anything else in plumbing — Philadelphia keeps its own legacy table entirely — so confirm the enforced code, edition, and amendments with your jurisdiction.

Common questions

What size water line do I need for my building?

Under the UPC table method: total the water supply fixture units, measure the developed length from the meter to the most remote outlet, and establish the available pressure after losses. In the 46–60 psi block at 100 feet, a 1" meter with a 1" supply carries 36 WSFU; a 1" meter with 1-1/4" supply carries 67. Read down the length column to the first row whose WSFU meets your total.

What size water meter for a house?

A typical single-family home lands between 10 and 20 WSFU under UPC Table 610.3. At 46–60 psi and up to 100 feet of developed length, a 3/4" meter with a 3/4" building supply covers 17 WSFU — which is why 3/4" × 3/4" is the standard small-house service and 1" supplies appear as fixture counts or run lengths grow.

Does higher water pressure let me use smaller pipe?

Yes, within limits — the table has three pressure blocks, and the same 1" × 1" pairing that carries 25 WSFU at 100 feet in the 30–45 psi block carries 39 over 60 psi. But pressure over 80 psi static requires a regulator, and the 2024 UPC cycle adds that sizing downstream of a regulator uses 80% of the regulator's set pressure.

Why doesn't the IPC have a water pipe sizing table like this?

The IPC body deliberately sizes water distribution by engineered design: pipe must deliver each fixture's minimum flow and pressure under peak demand (IPC 604.3), by an approved method. Its Appendix E provides a worked segmented-loss procedure — but appendices apply only where specifically adopted. The fixed IPC minimums that always apply are the per-fixture supply sizes of Table 604.5, on this page.

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