BRITISH STANDARD

BS EN

806-3:2006

Specifications for

installations inside

buildings conveying

water for human

consumption —

Part 3: Pipe sizing — Simplified method

The European Standard EN 806-3:2006 has the status of a

British Standard

ICS 91.140.60

12&23<,1*:,7+287%6,3(50,66,21(;&(37$63(50,77('%<&23<5,*+7/$:

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BS EN 806-3:2006

This British Standard was

published under the authority

of the Standards Policy and

Strategy Committee

on 28 April 2006

© BSI 2006

ISBN 0 580 48283 9

National foreword

This British Standard is the official English language version of

EN 806-3:2006. This part of BS EN 806 partially supersedes BS 6700:1997. On

publication of parts 1 to 5 of BS EN 806, BS 6700:1997 will be withdrawn.

NOTE EN 806 parts 1 to 5 have been agreed by CEN to be a “package” with a common Date of

Withdrawal for conflicting National Standards (Resolution CEN/BT/20/1993 and CEN/TC 164

Resolution 199 refer).

The UK participation in its preparation was entrusted by Technical Committee

B/504, Water supply, to Subcommittee B/504/2, Domestic installation design —

Internal, which has the responsibility to:

A list of organizations represented on this subcommittee can be obtained on

request to its secretary.
Cross-references
The British Standards which implement international or European

publications referred to in this document may be found in the BSI Catalogue

under the section entitled “International Standards Correspondence Index”, or

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Standards Online.
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Summary of pages
This document comprises a front cover, an inside front cover, the EN title page,

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EUROPEAN STANDARD

NORME EUROPÉENNE

EUROPÄISCHE NORM

EN 806-3

April 2006

ICS 91.140.60

English Version

Specifications for installations inside buildings conveying water

for human consumption - Part 3: Pipe sizing - Simplified method

Spécifications techniques relatives aux installations d'eau

destinée à la consommation humaine à l'intérieur des

bâtiments - Partie 3: Calculations des diamètres intérieurs -

Méthode simplifiée

Technische Regeln für Trinkwasser-Installationen -

Berechnung der Rohrinnendurchmesser - Teil 3:

Vereinfachtes Verfahren

This European Standard was approved by CEN on 3 February 2006.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.

CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
C O M I T É E U R O P É E N D E N O R M A L I S A T I O N
E U R O P Ä I S C H E S K O M I T E E F Ü R N O R M U N G

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2006 CEN

All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members.

Ref. No. EN 806-3:2006: E

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EN 806-3:2006 (E)

2

Contents

Page

Foreword......................................................................................................................................................................3

1

Scope ..............................................................................................................................................................4

2

Normative references ....................................................................................................................................4

3

Terms, symbols and units ............................................................................................................................4

4

Principles of pipe sizing calculations..........................................................................................................5

5

Simplified method of pipe sizing..................................................................................................................6

6

Special-installations ......................................................................................................................................8

Annex A (informative) Example for the determination of pipe sizes for standard-installations .......................9

Annex B (informative) Design flow rates in relation to total flow rates .............................................................12

Annex C (informative) List of national pipe sizing methods ...............................................................................14

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EN 806-3:2006 (E)

3

Foreword

This European Standard (EN 806-3:2006) has been prepared by Technical Committee CEN/TC 164 “Water
supply”, the secretariat of which is held by AFNOR.

This European Standard shall be given the status of a national standard, either by publication of an identical text or
by endorsement, at the latest by October 2006, and conflicting national standards shall be withdrawn at the latest
by October 2006.

NOTE

This is the third part of the European Standard (EN 806) consisting of five parts as follows:

Part 1: General

Part 2: Design

Part 3: Pipe sizing

Part 4: Installation

Part 5: Operation and maintenance

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.

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EN 806-3:2006 (E)

4

1 Scope

This European Standard is in conjunction with EN 806-1 and EN 806-2 for drinking water systems within premises.

This European Standard describes a calculation method for the dimensioning of pipes for the type of drinking water
standard-installations as defined in 4.2.

It contains no pipe sizing for fire fighting systems.

2 Normative

references

The following referenced documents are indispensable for the application of this document. For dated references,
only the edition cited applies. For undated references, the latest edition of the referenced document (including any
amendments) applies.

EN 806-1, Specifications for installations inside buildings conveying water for human consumption — Part 1:
General

EN 806-2, Specifications for installations inside buildings conveying water for human consumption — Part 2:
Design

3 Terms, symbols and units

This Clause is enlarged in completion to EN 806-1, to have in the field of pipe sizing the same definitions in
European standards.

Table 1 — Terms and definitions

Term Symbol

Unit

Explanation

(definition)

Flow-velocity v

m/s

Flow-rate, volume flow

Q

l/s
m

3

/h

Ratio of the volume of water passing through a specified flow
cross-section and the time required for this

Minimum flow-rate at draw-off point

Q

min

l/s

Flow-rate at draw-off point which is just sufficient for the
appliance to function

Draw-off flow-rate

Q

A

l/s

Assumed draw-off flow-rate at appliance for calculation
purposes

Total flow-rate

Q

T

l/s

Σ

Q

A

, sum of all draw-off flow-rates of the water appliances

supplied

Design flow-rate

Q

D

l/s

Flow-rate for hydraulic calculations, taking into consideration
the probable simultaneous demand

Static pressure

p

R

Pa

Gauge pressure at a measuring point in the water supply
system when no water flowing

Flow pressure

p

Fl

Pa

Gauge pressure at a measuring point in the water supply
system when water flowing

Minimum flow pressure

p

minFl

Pa

Gauge pressure required at the connection to a draw-off point
at its draw-off flow-rate

Pressure difference, head loss

∆

p

Pa

Difference in pressure between two points in the drinking water
installation, resulting from wall friction and individual head loss

(To be continued)

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EN 806-3:2006 (E)

5

Table 1 (concluded)

Term Symbol

Unit

Explanation

(definition)

Head loss as a consequence of difference
in elevation

∆

p

e

Pa -

Pipe length

I

m

-

Internal diameter of pipe

d

i

mm

-

External diameter of pipe

d

a

mm

-

Wall thickness of pipe

s

mm

-

Loading unit

LU

1

Factor taking into account the flow-rate required at an
appliance, the length of time the appliance is in use and the
frequency of use. One loading unit (1 LU) equalises a draw-off
flow rate Q

A

of 0,1 l/s.

4 Principles of pipe sizing calculations

4.1 General

Pipe sizing takes into consideration the character of the installation, the pressure conditions and the flow velocities.
This part includes the underground pipes within the premises.

4.2 Characters of installations

In a building there are standard-installations and special-installations.

An installation can be called a standard-installation, when:

•

the draw off flow rates do not exceed those set out in Table 2;

•

the kind of demand does not exceed the design flow-rate as shown in Figure B.1 (see Annex B);

•

it is not designed for continuous use of water. Continuous use being defined as use lasting more than
15 min.

Other installations are called special-installations.

4.3 Pressure

conditions

Static pressure at draw off point

max. 500 kPa

(Exception: garden/garage taps max. 1 000 kPa);

Flow pressure at draw off point

min. 100 kPa.

Several draw off points, e.g. thermostatic mixing valves, need a higher flow pressure. Calculations have to consider
this matter.

The difference between the static pressure at the lowest draw off point and the flow pressure at the hydraulic worst-
case draw off point, reduced by the pressure losses (resulting from wall frictions and individual head losses), give
the possible head of difference in elevation within a pressure section.

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EN 806-3:2006 (E)

6

4.4 Maximum flow velocities

The figures given in Table 3 are based on the following flow velocities:

header pipes, rising pipes, floor service pipes

max. 2,0 m/s;

connection pipes to one fitting (dead legs)

max. 4,0 m/s.

NOTE

National regulations may require lower flow velocities to avoid water hammer and noise.

5 Simplified method of pipe sizing

5.1 General

This clause shows a possibility for a simplified pipe sizing for standard-installations. This method can be used for all
type of buildings, which do not have measurements, which highly exceed the average. That means that in most of
the buildings the simplified method can be applied.

This method is equally used for cold and for hot water pipes.

5.2 Detailed

calculations

The designer is free to use a nationally approved detailed calculation method for pipe sizing (see Annex C).

5.3 Hot water return pipes

As hot water return pipes have to fulfil other hydraulic requirements, they cannot be sized with this method. The
flow-velocity in the hot water return pipes shall be calculated according to national or manufacturer’s
recommendation.

5.4 Loading

unit

1 loading unit (LU) is equivalent to a draw-off flow rate Q

A

of 0,1 l/s.

Table 2 — Draw-off flow-rates Q

A

, minimum flow-rates at draw-off points Q

min

and loading units for draw-

off points

Q

A

Q

min

Draw-off point

l/s l/s

Loading units

Washbasin, handbasin,
bidet, WC-cistern

0,1 0,1 1

Domestic kitchen sink, -
washing machine

a

, dish

washing machine, sink,
shower head

0,2 0,15 2

Urinal flush valve

0,3

0,15

3

Bath domestic

0,4

0,3

4

Taps /garden/garage)

0,5

0,4

5

Non domestic kitchen sink
DN 20, bath non domestic

0,8 0,8 8

Flush valve DN 20

1,5

1,0

15

a

For non domestic appliances check with manufacturer.

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EN 806-3:2006 (E)

7

The values in this Table do not correspond with the values in product norms. They are only used for pipe sizing.

5.5 Application of the simplified method

Beginning at the last draw-off point, the loading units for each section of the installation have to be determined. The
loading units must be added. The probability of simultaneous demand has been taken into consideration in Tables
3.1 to 3.8. Depending on the material chosen by the designer the pipe size can now be taken out of Tables 3.1 to
3.8. The design flow-rate Q

D

as given in Figure B.1 is taken into account for the values in Tables 3.1 to 3.8.

Table 3 — Loading units for determination of pipe diameters

Table 3.1 — Hot-dip galvanised steel

Max.

load

LU

6

16 40 160 300 600 1

600

Highest value

LU

4

15

DN

15 20 25 32 40 50 65

d

i

mm

16 21,6 27,2 35,9 41,8 53 68,8

Max length of
pipe

m

10

6

Table 3.2 — Copper

Max.

load

LU 1 2 3 3 4 6 10

20

50

165

430

1

050 2

100

Highest

value LU 2 4 5

8

d

a

x s

mm

12 x 1,0

15 x 1,0

18 x 1,0 22 x 1,0 28 x 1,5 35 x 1,5 42 x 1,5 54 x 2 76,1 x 2

d

i

mm

10,0

13,0

16,0

20,0

25 32 39 50

72,1

Max length of
pipe

m 20 7 5 15 9 7

Table 3.3 — Stainless steel

Max.

load LU

3

4

6 10 20 50 165 430 1

050

2

100

Highest

value

LU

4

5 8

d

a

x s

mm

15 x 1,0

18 x 1,0 22 x 1,0 28 x 1,2 35 x 1,5 42 x 1,5 54 x 1,5 76,1 x 2

d

i

mm

13,0

16,0

19,6

25,6

32 39 51 72,1

Max

length

of

pipe

m

15

9

7

Table 3.4 — PE-X

Max.

load

LU 1 2 3

4

5

8

16 35 100 350

700

Highest

value LU 4 5

8

d

a

x s

mm

12 x 1,7

16 x 2,2

20 x 2,8 25 x 3,5 32 x 4,4 40 x 5,5 50 x 6,9

63 x 8,6

d

i

mm 8,4

11,6

14,4 18,0 23,2 29 36,2 45,6

Max

length

of

pipe

m

13

4

9

5

4

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EN 806-3:2006 (E)

8

Table 3 (concluded)

Table 3.5 — PB

Max.

load

LU 1 2 3 3 4 6 13

25

55 180

500

1

100

Highest

value LU 2 4 5

8

d

a

x s

mm

12 x 1,3

16 x 1,5

20 x 1,9 25 x 2,3 32 x 3 40 x 3,7 50 x 4,6 63 x 5,8

d

i

mm 9,4

13,0

16,2 20,4 26 32,6 40,8 51,4

Max

length

of

pipe

m

20

7

5

15

9

7

Table 3.6 — PP

Max.

load

LU 1 2 3 3 4 6 13

30

70

200

540

970

Highest

value LU 2 4 5

8

d

a

x s

mm

16 x 2,7

20 x 3,4

25 x 4,2 32 x 5,4 40 x 6,7 50 x 8,4 63 x 10,5

75 x 12,5

d

i

mm 10,6

13,2

16,6 21,2 26,6 33,2 42

50

Max length of pipe m

20 12 8

15 9

7

Table 3.7 — PVC-C

Max.

load

LU 3 4 5 10

20

45

160

420

900

Highest value

LU

4

5

8

d

a

x s

mm

16 x 2,0

20 x 2,3

25 x 2,8

32 x 3,6

40 x 4,5

50 x 5,6

63 x 6,9

d

i

mm

12,0

15,4 19,4 24,8 31 38,8 49,2

Max length of pipe m

10 6

5

Table 3.8 — PEX/AL/PE-HD resp. PE-MD/AL/PE-HD

Max.

load

LU 3 4 5 6

10 20 55 180 540 1

300

Highest

value

LU

4

5 5 8

d

a

x s

mm

16 x 2,25/16 x 2,0

18 x 2

20 x 2,5 26 x 3

32 x 3

40 x 3,5 50 x 4

63 x 4,5

d

i

mm

11,5/12,0

14 15 20 26 33 42 54

Max

length

of

pipe

m

9

5

4

For materials not mentioned in the tables, the table with the most similar material and in this table the column with
the most similar or equal diameter shall be chosen.

6 Special-installations

Special-installations are installations, which do not fulfil the conditions for standard-installations or if the building
has measurements, which highly exceed the average.

There are installations, where only parts of the project shall be called special-installations. In these cases the parts
which fulfil the conditions for standard-installations can be sized with the simplified method.

Pipes for special-installations shall be sized by nationally approved detailed calculations (see Annex C).

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9

Annex A

(informative)

Example for the determination of pipe sizes for standard-installations

Figure A.1 — Example for standard-installation

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EN 806-3:2006 (E)

10

Appliance

Beginning at the end of the pipe the loading units must be added. Resulting from this calculation the size of that
part of the pipe can be determined.

Task according to the drawing

The cold water pipe from the under ground floor to the draw-off points has to be sized.

The pipe shall be in hot-dip galvanised steel.

In every apartment the following draw-off points will be installed:

1 domestic bath

1 WC-cistern

1 washbasin

1 domestic kitchen sink

There are five equal apartments.

Result

Find the loading units from Table 2:

1 domestic bath

4 LU

1 WC-cistern

1 LU

1 washbasin

1 LU

1 domestic kitchen sink

2 LU

Part 1

connected is

1 domestic kitchen sink

=

2 LU

Table 3.1 demands for 2 LU

=

DN 15

Part 2

connected are

1 domestic kitchen sink

=

2 LU

1 domestic bath

=

4 LU

total

=

6

LU

Table 3.1 demands for 6 LU

=

DN 15

Part 3

connected are

1 domestic kitchen sink

=

2 LU

1 domestic bath

=

4 LU

1

washbasin

=

1

LU

total

=

7

LU

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Table 3.1 demands for 7 LU

=

DN 20

Part 4

connected are

1 domestic kitchen sink

=

2 LU

1 domestic bath

=

4 LU

1

washbasin

=

1

LU

1

WC-cistern

=

1

LU

total per apartment

=

8 LU

Table 3.1 demands for 8 LU

=

DN 20

Part 5

connected are

2 apartments

=

16 LU

Table 3.1 demands for 16 LU

=

DN 20

Part 6

connected are

3 apartments

=

24 LU

Table 3.1 demands for 24 LU

=

DN 25

Part 7

connected are

4 apartments

=

32 LU

Table 3.1 demands for 32 LU

=

DN 25

Part 8

connected are

5 apartments

=

40 LU

Table 3.1 demands for 40 LU

=

DN 25

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12

Annex B

(informative)

Design flow rates in relation to total flow rates

The diagram (Figure B.1) shows a possibility to determine the design flow-rate Q

D

from

Σ

LU for standard-

installations. Where nationally approved further such diagrams (e.g. for various types of buildings) may be used.

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EN 806-3:2006 (E)

13

Key
1 Design flow rate Q

D

2 Total flow rate Q

T

in LU

3 Example of highest single value LU

Figure B.1 — Design flow rate Q

D

in l/s for standard-installations in relation to the total flow rate Q

T

in LU

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14

Annex C

(informative)

List of national pipe sizing methods

The following survey gives information about existing national calculation methods which can be used as an
alternative to this European Standard or in cases where reasons for differentiated pipe sizing are given e.g. for big
buildings, industrial and commercial plants etc. If any other national calculation methods exist, which are not listed
here, it is recommended that the national standardization body should give information in the foreword of the
national edition of EN 806-3.

Table C.1 — National pipe sizing methods

Country Document

No Title

Austria

ÖNORM B 2531-2

Trinkwasserversorgungseinrichtungen in
Grundstücken; Bemessung der Rohrleitungen

Denmark

DS 439

Code of Practice for domestic water supply installations

Finland

National Building Code of
Finland, D1

Water supply and drainage installations for buildings —
Regulations and recommendations 1987

France

NF P40-202
(ref DTU 60.11)

Règles de calcul des installations de plomberie sanitaire et des
installations d'évacuation des eaux pluviales

Germany

DIN

1988-3

Technische Regeln für Trinkwasser-Installationen (TRWI);
Ermittlung der Rohrdurchmesser; Technische Regel des DVGW

The Netherlands

VEWIN Working Sheets
WB 2.1
WB 2.1 A

WB 2.1 C
WB 2.1 G

Principles of calculation: General and overview
Principles of calculation: Flow rate and working pressures for
tapware and apparatus
Principles of calculation: Calculation and design criteria
Principles of calculation and tables for determining pressure
losses in pipes

Spain

Código Técnico de la
Edificatión, Sección HS4
PNE 149201

Suministro de agua
Abastecimiento de agua. Dimensionamiento de instalaciones
interiores de agua

United Kingdom

BS 6700:1997

Specification for design, installation, testing and maintenance of
services supplying water for domestic use within buildings and
their curtilages

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