Microscopic Particulate Analysis

Microscopic Particulate Analysis (MPA) for:

  • Groundwater Under the Direct Influence (GWUDI)
  • Flitration Plant Optimization

Microscopic Particulate Analysis (MPA) can be used to help assess a groundwater source is under the direct influence (GWUDI) of surface water (and thereby at risk of contamination) and also for Filter Plant Optimization (FPO).


The EPA Consensus Method (EPA 910-9-92-029, Oct. 1992) uses identification and enumeration of surface water “bioindicators" (e.g., algae) to generate a risk rating score that indicates the likelihood that the groundwater is under the direct influence of surface water.

Although not strictly part of the MPA method, typically a portion of the pellet is also processed for Cryptosporidium and Giardia detection using procedures from EPA Method 1623 (EPA 821R01025).

ASI provides everything needed (sampling unit, filter, instructions, etc.) for typical MPA sample collection, which involves filtration of at least 500 gallons of water and overnight shipment of the filter to ASI.

We understand the impact of MPA results on water suppliers and communities nationwide that rely on groundwater sources. Therefore, we provide our clients with detailed reports that describe the MPA methodology, tabular data and interpretation of their sample results. As with our other services, our senior technical staff is available to answer any questions regarding MPAs and to provide consulting services as requested. 


A variation of MPA procedure (EPA 910/R-96-001, Apr. 1996) can be used to assess and optimize filtration plant performance by collection and analysis of raw and filtered water samples.  Biological particulates in each sample are identified and counted within discrete size classes and the resulting data used to calculate log reduction of biological particulates for each size class as a measure of plant performance. 

For more information, please click HERE for ASI’s technical document regarding Microscopic Particulate Analysis or contact our Clients Services team.