MAJOR CHANGES to City of Houston Drainage and Detention

Houston Building Permits News • January 22, 2021


he City of Houston has adopted new storm water detention requirements, which significantly increase on-site detention standards. It sounds like any Houston building permitting project submitted for initial review after April 1st, 2021 ( Initially was February 4th, 2021 ) will have to adhere to these requirements. This has been in the works for some time for commercial projects, due to Harris County demands and other issues with flooding and overdevelopment; we knew something was coming. As for Residential, this was completely out of the blue and not expected. Based on conversations we have had this week, the GHBA is directly involved in supporting the reversal of this mandate on Houston Drainage and Detention requirements.


Check out the cover letter>> and IDM documents >> for your review and below is a gist of the changes.

  • 1) Residential projects that are *OVER 7,500 Sf lot size and/or 65% impervious cover will be required to provide engineered drainage and detention. (The current lot size is 15,000 Sf or greater)

  • 2) For tracts smaller than 1 acre, the new requirement is 0.75 ac-ft/ac. This is 3.75 times higher than the current rate.

  • 3) For tracts larger than 1 acre but less than 20 acres, the rate is based on the percentage of final impervious cover on the site. The minimum rate is 0.75 ac-ft/ac and it gets higher as the percentage of impervious cover increases.

  • 4) For tracts larger than 20 acres, detention will be required based on the current Harris County Flood Control District requirements.

What you can do

We are asking for your support. Everyone can help by calling your City Council member – Carol Haddock’s office, Mayor Sylvester Turner, Developers and their clients to voice any concern about these changes.

Please contact us if you have any questions, we are here to support you with Houston Building Permits any way we can! Call 713-369-0925

(*Updated 3/17/2021)