| Year | Type of Credit | Rating Agency | Credit Rating | Rating Outlook | Download |
|---|---|---|---|---|---|
| Date | |||||
| 2022 | |||||
| 29 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2021 | |||||
| 29 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2020 | |||||
| 30 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2019 | |||||
| 29 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2018 | |||||
| 29 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2017 | |||||
| 04 Dec | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2016 | |||||
| 16 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2015 | |||||
| 30 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 06 May | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 08 Jan | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2014 | |||||
| 13 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2013 | |||||
| 16 Dec | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2012 | |||||
| 06 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 07 Feb | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2011 | |||||
| 10 Oct | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2010 | |||||
| 03 Nov | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2009 | |||||
| 29 Oct | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 17 Feb | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 28 Jan | Company Rating / Issue Rating | Tris Rating | AA- | Stable | Download |
| 2008 | |||||
| 22 Aug | Company Rating | Tris Rating | AA- | Stable | Download |
Remark - In 2014, "Thai Tap Water Public Company Limited" has changed its name to TTW Public Company Limited