Print PageTests for toxic chemicals will be carried out today at homes near the Holden plant at Elizabeth in Adelaide's north.
The crawlspace under 40 houses was tested in August after industrial chemicals were found in groundwater under the plant last year.
The results of those tests found levels of trichloroethylene (TCE) and perchloroethylene (PCE) were within accepted limits.
The Environment Protection Authority says it wants to compare the results of the current tests with those done in August to see if there is any seasonal variation.
The contamination dates back decades and Holden has warned residents not to use groundwater.
