Chromium (total)
Norwalk Water Department
Chromium is a naturally occurring metal, but industrial uses can elevate its levels in water. One form, hexavalent chromium, causes cancer. Total chromium is not a good indicator of the amount of hexavalent chromium in drinking water.
43
Samples
0
Samples exceeding legal limit (MCL)
0
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2013 | 0.406 ppb | 36 | 12 | ND - 1.70 ppb |
| 2014 | ND | 2 | 0 | ND |
| 2015 | ND | 1 | 0 | ND |
| 2016 | N/A | 0 | 0 | N/A |
| 2017 | ND | 2 | 0 | ND |
| 2018 | N/A | 0 | 0 | N/A |
| 2019 | ND | 2 | 0 | ND |
ppb = parts per billion
State and national drinking water standards and health guidelines
EPA Maximum Contaminant
Level (MCL) 100 ppb
The legal limit for total chromium, established in 1991, was based on a 1958 toxicity study in laboratory animals, and applies to both the less-toxic trivalent chromium and the more-toxic hexavalent chromium forms of this compound. This limit does not protect against the risk of cancer from ingestion of hexavalent chromium.
ppb = parts per billion
All test results
| Date | Lab ID | Result |
|---|---|---|
| 2013-01-31 | 2774527 | 1.30 ppb |
| 2013-01-31 | 2774519 | ND |
| 2013-01-31 | 2774523 | 0.600 ppb |
| 2013-01-31 | 2774511 | ND |
| 2013-01-31 | 2774521 | ND |
| 2013-01-31 | 2774525 | 1.30 ppb |
| 2013-01-31 | 2774515 | ND |
| 2013-01-31 | 2774517 | ND |
| 2013-01-31 | 2774513 | ND |
| 2013-01-31 | 2774507 | 1.50 ppb |
| 2013-01-31 | 2774505 | 1.40 ppb |
| 2013-01-31 | 2774509 | ND |
| 2013-04-30 | 2818650 | 0.400 ppb |
| 2013-04-30 | 2818648 | ND |
| 2013-04-30 | 2818630 | ND |
| 2013-04-30 | 2818634 | ND |
| 2013-04-30 | 2818626 | ND |
| 2013-04-30 | 2818632 | ND |
| 2013-07-29 | 2869380 | 1.70 ppb |
| 2013-07-29 | 2869384 | 1.60 ppb |
| 2013-07-29 | 2869388 | ND |
| 2013-07-29 | 2869372 | ND |
| 2013-07-29 | 2869351 | ND |
| 2013-07-29 | 2869368 | ND |
| 2013-07-29 | 2869360 | ND |
| 2013-07-29 | 2869295 | 1.60 ppb |
| 2013-07-29 | 2869376 | 0.500 ppb |
| 2013-07-29 | 2869342 | ND |
| 2013-07-29 | 2869323 | ND |
| 2013-07-29 | 2869306 | 1.70 ppb |
| 2013-10-29 | 2922262 | ND |
| 2013-10-29 | 2922271 | ND |
| 2013-10-29 | 2922290 | ND |
| 2013-10-29 | 2922303 | 1.000 ppb |
| 2013-10-29 | 2922297 | ND |
| 2013-10-29 | 2922282 | ND |
| 2014-07-23 | 9588-003-1010 | ND |
| 2014-07-23 | 9588-002-1025 | ND |
| 2015-04-23 | 9588-012-0947 | ND |
| 2017-07-24 | 9588-002-1028 | ND |
| 2017-07-24 | 9588-003-0955 | ND |
| 2019-05-24 | 9588-012-0920 | ND |
| 2019-07-25 | 9588-002-1035 | ND |