As an energy engineer focused on energy efficiency in the built environment, I am familiar with the standards and codes covering energy use in buildings; specifically ASHRAE 90.1, the "Energy Standard for Buildings," and IECC 2018, the "International Energy Conservation Code."

Recently several areas of increasing concern are intersecting with this work, such as indoor air quality, but also stormwater management:

Stormwater management is the effort to reduce runoff of rainwater or melted snow into streets, lawns and other sites and the improvement of water quality, according to the United States Environmental Protection Agency (EPA). (Source)

My question is what engineering codes and/or standards govern stormwater management in and around buildings?

Some teams we work with are concerned about how to manage the water which falls on the roof of the buildings they are designing. Are there guidelines related to collecting and/or treating this water before diverting it?

Note: my work is within the U.S., but I'm also interested to know of standards or codes that are in use in other countries.

  • 1
    $\begingroup$ Are we meant to assume the USA here? $\endgroup$
    – Solar Mike
    Oct 18, 2018 at 18:56
  • $\begingroup$ @SolarMike I edited the question. I'm most interested in the USA but would be interested to know what's in use elsewhere as well. $\endgroup$
    – LShaver
    Oct 18, 2018 at 19:25
  • $\begingroup$ Plumbing codes and building codes provide some guidance, but code adoption is at the descretion of the municipality, so there is no one-size-fits-all answer. ASHRAE and the ICC came out with a green building/sustainability model code which may have some guidance since water collection is an aspect of LEED, but I’m not sure because I don’t have access to a copy. Even so, there are going to be very few places, if anywhere, that have adopted it despite being called a “code” $\endgroup$
    – Secundus
    Nov 18, 2018 at 2:51
  • $\begingroup$ To clarify, the documents I mentioned are the International Green Construction Code (IgCC) and ASHRAE 189.1. As mentioned before, they are model codes and only recently released, so they will not be actual codes almost anywhere. $\endgroup$
    – Secundus
    Nov 18, 2018 at 2:55

2 Answers 2


I came across a project with stormwater requirements referenced to the code I was trying to identify -- the International Plumbing Code. Two chapters are relevant to what I've been trying to find.

Chapter 11, Storm Drainage:

About this chapter: Rainfall onto buildings must be removed and directed to a location that can accommodate storm water. Chapter 11 specifies the design rainfall event for the geographic area and provides sizing methods for piping and gutter systems to convey the storm water away from the building. Included in this chapter are regulations for piping materials and subsoil drainage systems.

Chapter 13, Nonpotable Water Systems:

About this chapter: Storm water and some liquid waste from a building can be a source of nonpotable water that can be used to reduce the volume of potable water supplied to the building. Chapter 13 provides the requirements for storage, treatment and distribution of this resource. This chapter also regulates the piping systems for reclaimed water supplied by a wastewater treatment facility.


I answer this with a perspective from the United Kingdom. With an annual problem of flooding of low-lying areas especially in the Worcester area West of Birmingham the national government has written new laws that specified new housing estates and construction sites must hold 50% of water runoff and prove it before building planning can be approved. As far as I am aware there are no building codes in the eurocodes that specifically deal with stormwater runoff. More often than not stormwater runoff is dealt with by means of concrete structures that are inserted underground such as pipeworks and drainage ditches and even urban rivers lined with concrete. from this perspective, such structures are covered by Eurocode 1 and 2.

This document maybe of use to you in this regard. [Stormwater management][1]. An important consideration is that maybe stormwater should be dealt with in a more effective ways such as pipes that have holes to allow them to act as soakaways on route to a river and thereby allowing the ground that they are buried in to absorb a fair amount of water before actually reaches the river system

[1]: https://ec.europa.eu/research/participants/documents/downloadPublic?documentIds=080166e5a5630bbf&appId=PPGMS ""


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