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Water Service Line - Sizing

TO CALCULATE SIZE OF WATER SERVICE LINE
The water service supply line delivers potable water to your home from the city water main. The water service line for a residential home is typically a ¾” to 1” pipe that can be seen entering your building near the water meter. If you are proposing to add plumbing fixtures such as a new shower, new sink, new toilet, or similar, it is required by the Illinois Plumbing Code that the water service supply line is large enough to accommodate the capacity of water that is demanded from all of your plumbing fixtures combined as established in Table N (Flush Tank) or TABLE O (Flushometer) of the Illinois Plumbing Code. At an existing residence, several conditions can affect the capacity of the water service line including pipe size, length of water service line, and condition of the pipe. To determine if the existing water service supply line is adequately sized you will need three pieces of information:

  1. TABLE A - Water Service Line-Sizing Worksheet - is attached and allows you to calculate the number of existing and proposed plumbing fixtures within your home as well as any possible future plumbing fixtures. For each fixture, there is a corresponding Water Supply Fixture Unit (WSFU). The worksheet will allow you to calculate the total WSFU’s by multiplying in each row the number of fixtures by the WSFU’s and then adding all the WSFU’s in the right-hand column. The total will then be compared to TABLE N or TABLE O.
  2. TABLE N or TABLE O - which is also attached is from the Illinois Plumbing Code and identifies the minimum water service line or “pipe size” (third column) based on the total number of WSFU’s calculated from TABLE A. Please Note: TABLE N should be referenced if toilets are tank type and TABLE O should be referenced if toilets are flushometer type.
  3. PIPE SIZE - of the existing water service line to your home is best determined by measuring the pipe where it enters the building. You may also call the Wheaton Water Division at 630-260-2090, who may be able to confirm the size of the existing water service line.

If the proposed addition of plumbing fixtures to an existing residence results in more fixtures than supported by the water service as determined by TABLE N/O the capacity of the water service line is undersized and does not comply with Illinois Code. Please forward TABLE A to the Wheaton Building Department and staff will forward to the Water Division to confirm if the existing water service line is in compliance with Illinois Code.

OPTIONS IF WATER SERVICE LINE IS UNDERSIZED
Option 1 - Replacement. If the proposed addition of plumbing fixtures to an existing residence results in more fixtures than supported by the water service line, the line shall be replaced from the City water main to the meter. Prior to commencing the installation of any new, repair, or replacement of any existing water service line a permit is required to be issued by the Wheaton Building Department, see the handout titled "Water Service Line - New, Repair, Disconnect;" or

Option 2 - Pressure Test. If the proposed addition of plumbing fixtures to an existing residence results in more fixtures than supported by the water service line the capacity of the water service line can be evaluated by an alternate method and that is by having your plumber perform a pressure test. The pressure test may have been stipulated when the Building Department issued the building permit to you. Section 890.1210c of the Plumbing Code requires a minimum constant water pressure on the discharge side of the water meter to be at least 20 p.s.i. The water distribution system must be adequately sized to provide a minimum constant water pressure at each fixture of at least 8 p.s.i. The pressure test is conducted after the installation of the additional fixtures and must be conducted by a registered plumbing contractor and witnessed by the City’s registered plumbing inspector.

The pressure test shall be conducted as follows:

  1. Notify the Building Department at least one day in advance that you will be performing a pressure test with your Plumbing Contractor and pay $40.00 to have the City Plumbing Inspector witness the pressure test. Pressure tests are typically scheduled on each Tuesday at approximately 9:00 a.m. Pressure tests shall be performed no sooner than after the plumbing rough inspection and can be done on the same day as the final plumbing inspection.
  2. On the day of the pressure test: locate all water outlets and toilets in the house.
  3. Find the sill cock or drain cock located closest to the water meter and attach the pressure gauge. Open the sill cock fully and record the static pressure.
  4. Turn on all plumbing fixtures, both hot and cold. Start in the basement, if applicable, and work up to the top floor. Do not open other sill cocks or yard hydrant.
  5. Flush all toilets and record the residual pressure while the toilets are still filling.

If the pressure falls below 20 p.s.i., the water service must be replaced, see Option 1 above. If the pressure test finds that the water pressure at the water service entrance is maintained at no less than 20 p.s.i. at peak demand, the water service line size complies with State Plumbing Code and does not need to be replaced. Money that was collected by the City for the installation of the proposed new water service line may be eligible for a refund. These fees may include costs for a larger water meter, inspection fees, the cost for replacement of a water service line from main to B-box, restoration bonds, and others. To initiate a refund send a copy of the inspection report that indicates the pressure at the water meter exceeds the required State Plumbing Code pressure to the Water Division. The Water Division will review your request, identify all fees that can be refunded, and will then forward the information to the Building Department for processing of the refund.

TABLE A - WATER SERVICE LINE SIZING WORKSHEET

Instructions: This document is a form-fillable PDF that automatically calculates the Water Service Fixture Unit (WSFU) Count if using the free Adobe Acrobat PDF Reader software to view and fill out. Where existing fixtures are only being replaced with no other work involved, the fixture is to be included only as “existing,” do not add these fixtures as “proposed.” If your plans depict “future” fixtures, they are to be included as “proposed” fixtures to ensure that the water service line is properly sized. 
** PLEASE NOTE: If this worksheet is to be used for Commercial projects - Commercial Load Values must be provided. Once completed, please print the document, provide signature, and include it in your Permit Submittal Package delivered to the City of Wheaton.

TABLE N - Flush Tank 
 TITLE 77: PUBLIC HEALTH / PART 890 ILLINOIS PLUMBING CODE 

 Section 890.APPENDIX A Plumbing Materials, Equipment, Use Restrictions and Applicable Standards 
 Section 890.TABLE N Water Service Line-Sizing for a Supply System with Flush Tank.

W.S.F.U.
Demand (GPM)
Pipe Size (Inches)
Pressure Loss (PSI / 100' of Pipe)
Velocity (Ft. / Sec.)
Meter Size (Inches)
2
2
½"
4.2
2.7
⅝"
4
3
½"
8.7
4.2
⅝"
6
5
½"
22.5
7.0
⅝"
8
6.5
¾"
6.3
4.3
⅝"
10
8
¾"
9.0
5.4
¾"
12
9.2
¾"
11.5
6.1
¾"
14
10.4
¾"
15.0
6.9
¾"
16
11.6
¾"
18.0
7.7
¾"
20
14
1"
7.2
5.6
¾"
25
17
1"
10.0
6.6
¾"
30
20
1"
13.6
8.0
1"
35
22.5
1¼"
5.8
5.7
1"
40
25
1¼"
7.0
6.3
1"
45
27
1¼"
8.2
6.9
1"
50
29
1¼"
9.5
7.4
1"
60
32
1½"
5.0
5.8
1½"
70
35
1½"
6.2
6.4
1½"
80
38
1½"
7.0
7.2
1½"
90
41
1½"
8.0
7.5
1½"
100
43.5
1½"
8.7
7.8
2"
120
48
2"
2.7
5.0
2"
140
52.5
2"
3.1
5.4
2"
160
57
2"
3.6
5.8
2"
180
61
2"
3.9
6.1
2"
200
65
2"
4.5
6.6
2"
225
70
2"
5.2
7.1
2"
250
75
2"
6.0
7.7
3"
275
80
2½"
2.6
5.5
3"
300
85
2½"
2.9
5.8
3"
350
95
2½"
3.5
6.5
3"
400
105
2½"
4.2
7.1
3"
450
115
2½"
5.0
8.0
3"
500
125
3"
2.3
5.9
3"
600
145
3"
3.1
6.8
4"
750
170
3"
4.0
8.0
4"
1000
208
4"
1.5
5.7
4"
1250
240
4"
1.9
6.4
4"
1500
267
4"
2.3
7.0
4"
1750
294
4"
2.8
7.8
4"
2000
320
6"
0.36
3.7
6"

TABLE O - Flushometer 
 TITLE 77: PUBLIC HEALTH / PART 890 ILLINOIS PLUMBING CODE 

 Section 890.APPENDIX A Plumbing Materials, Equipment, Use Restrictions and Applicable Standards 
 Section 890.TABLE O Water Supply Fixture Units (W.S.F.U.) for a Supply System with Flushometers.

W.S.F.U.
Demand (GPM)
Pipe Size (Inches)
Pressure Loss (PSI / 100' of Pipe)
Velocity (Ft. / Sec.)
Meter Size (Inches)
10
27
1¼"
8.3
6.8
¾"
12
28.6
1¼"
9.2
7.2
¾"
14
30.2
1¼"
10
7.9
¾"
16
31.8
1¼"
11
8.0
¾"
20
35
1½"
6.0
6.4
¾"
25
38
1½"
7.0
6.9
1"
30
41
1½"
8.0
7.4
1"
35
43.8
1½"
8.8
8.0
1"
40
46.5
2"
2.5
4.7
1"
45
49
2"
2.7
5.1
1"
50
51.5
2"
2.9
5.4
1½"
60
55
2"
3.4
5.8
1½"
70
58.5
2"
3.7
6.0
1½"
80
62
2"
4.0
6.2
1½"
90
64.8
2"
4.6
6.5
1½"
100
67.5
2"
5.0
6.8
1½
120
72.5
2"
5.6
7.2
2"
140
77.5
2"
6.3
8.0
2"
160
82.5
2½"
2.7
5.7
2"
180
87
2½"
3.0
6.1
2"
200
91.5
2½"
3.4
6.4
2"
225
97
2½"
3.7
6.8
2"
250
101
2½"
4.0
7.1
3"
275
106
2½"
4.2
7.3
3"
300
110
2½"
4.6
7.6
3"
350
119
3"
2.1
5.5
3"
400
126
3"
2.3
5.9
3"
450
138
3"
2.7
6.3
3"
500
145
3"
3.0
6.8
3"
600
160
3"
3.6
7.4
4"
750
178
4"
1.1
4.7
4"
1000
208
4"
1.5
5.6
4"
1250
240
4"
1.9
6.4
4"
1500
267
4"
2.3
7.0
4"
1750
294
4"
2.8
7.8
4"
2000
321
6"
0.4
3.7
6"

Revised 1/18/2011