Cryptosporidium and Giardia in Water...a source of information & perspective
This website is owned, operated, and maintained by Jerry Ongerth, Phd, PE to make available new and developing information on Cryptosporidium and Giardia in water along with older still relevant information.
Key issues facing water utilities and regulatory agencies include determining the occurrence of Cryptosporidium and Giardia in water...and ultimately determining their significance. Information provided here has been generated through work conducted by Dr. Ongerth for water utilities and regulatory agencies and published in prominent scientific journals or is available in work by others that is published or available on the web. Basic information is provided below in the form of journal articles describing:
In mid July of 2012 the USEPA released the Cryptosporidium occurrence data generated in the LT2ESWTR (LT2) monitoring. The data were summarized briefly and rather superficially in presentations to a stakeholder meeting held on Dec. 12, 2011. The presentations summarizing the LT2 data on Matrix Spike Recovery
and on Cryptosporidium Occurrence are included in links here. Independent analysis of the data is a major project. The results of initial analysis looking specifically at the data from individual sampling sites have now (May 7, 2013) in Environmental Science and Technology. During analysis of the LT2 data it was realized that the ICR Supplemental Survey data had never been examined on a site by site basis. Completion of that analysis has now also been published on-line, Aug. 14, 2013, in Environ Sci Technol (see Item 6 in list above).
Issues of critical importance to the water industry regarding the occurrence include:
Recently completed manuscripts are included below describing
Key issues facing water utilities and regulatory agencies include determining the occurrence of Cryptosporidium and Giardia in water...and ultimately determining their significance. Information provided here has been generated through work conducted by Dr. Ongerth for water utilities and regulatory agencies and published in prominent scientific journals or is available in work by others that is published or available on the web. Basic information is provided below in the form of journal articles describing:
- The concentration of Giardia cysts found water sources of Seattle and Tacoma, WA
- A description of the first ever finding of Cryptosporidium...in surface water near Seattle WA
- Description of the concentration of Cryptosporidium in a river near Seattle WA demonstrating its continuous (as opposed to intermittent) presence.
- The role of recovery efficiency in Cryptosporidium and Giardia monitoring and its importance to describing their concentrations in water. (Water Research, 47(7):2479-2488, May 1, 2013).
- LT2 Cryptosporidium Data: What do they tell us about Cryptosporidium in surface water in the United States? (Environ Sci & Technol, 47(9):4029-4038), May 7, 2013)
- ICR SS Protozoan Data Site-by-Site--A Picture of Cryptosporidium & Giardia in USA Surface Water. (Environ. Sci. Technol., 47(18):10145-10154, Sept 17, 2013 DOI: 10.1021/es4027503
- WHITE PAPER--Essential Information to Consider in the 6-Year Review of The Long Term (2) Enhanced Surface Water Treatment Rule (LT2). Comments submitted to USEPA, July 26, 2013
- A description of the scope and range of Cryptosprodium and Giardia ocurrence in water. This understanding is essential to understanding the risk at any sampling location in relation to findings at sampling locations throughout the USA. J. Environmental Engineering (on-line, Sept 2016) (http://dx.doi.org/10.1061/(ASCE)EE.1943-7870.0001161)
- Descripton of LAMP applied to monitoring Cryptosporidium and Giardia in water samples...a presentation prepared for the AWWA-WQTC 2014.
In mid July of 2012 the USEPA released the Cryptosporidium occurrence data generated in the LT2ESWTR (LT2) monitoring. The data were summarized briefly and rather superficially in presentations to a stakeholder meeting held on Dec. 12, 2011. The presentations summarizing the LT2 data on Matrix Spike Recovery
and on Cryptosporidium Occurrence are included in links here. Independent analysis of the data is a major project. The results of initial analysis looking specifically at the data from individual sampling sites have now (May 7, 2013) in Environmental Science and Technology. During analysis of the LT2 data it was realized that the ICR Supplemental Survey data had never been examined on a site by site basis. Completion of that analysis has now also been published on-line, Aug. 14, 2013, in Environ Sci Technol (see Item 6 in list above).
Issues of critical importance to the water industry regarding the occurrence include:
- The reasons for not finding Cryptosporidium in 93% of LT2 samples...were they really present but below the limit of detection? Or were they simply not there?
- How can zero...below limit of detection...analytical results be avoided...providing real value for the cost of every sample...ca $500?
- Why has the EPA through application of Method 1622/.23 not used the Matrix Spike as a measure of recovery efficiency and required using it to calculate concentration?
- Is the measurement of concentration important...or is the occurrence of Cryptosporidium and Giardia adequately described by raw numbers?
- What do data on true concentrations of Cryptosporidium and Giardia look like and what do they tell us?
Recently completed manuscripts are included below describing
- A simple means of counting and manipulating small numbers of Cryptosporidium and of Giardia essential to efficient recovery efficiency measurement; and
- A fresh look at the skewed distribution of discrete organisms (Cryptosporidium oocysts and Giardia cysts) at low concentration and its implications for measuring Cryptosporidium and Giardia concentrations.
- An evaluation of Poisson-distributed Cryptosporidium & Giardia in reservoirs illustrating the proper application of Poisson distribution to sampling planning and data interpretation. The question of interpreting finding no (zero) organisms in Method 1622/1623 analysis results is clarified.
- A description of typical data on Cryptosporidium and Giardia in water highlighting features pertaining to design and implementation effective sampling that will produce data useful to watershed and water quality management.