In MARSOLut Project, Tragsa partner have been considering the willingness of MAR Standards based on Maximum allowable Concentrations (MACs) in MAR guidelines at national level.
There have been analyzed 22 international MAR-related laws, guidelines, even operator rules. After that, 13 MAR sites in Spain (all those from which we have been able to gather analitycal results) have been benchmarked. Most of the cases breach any parameters, whilst they are succesful MAR sites and have a permission or allowance from waterauthorities. E.g. in one case, MAR water has about 50 ppm of nitrate concentrations, recharging an aquifer that exceeds100 ppm, what entails a profitable environmental impact (despite it overpasses most of the MAC-based standars).
Some alternative suggestions are analyzed and proposed in the article. The final target is the CIS GW WG to consider this study prior publishing the final version of the MAR guidelines for Europe (not a Directive due to the veto of two European States).
Please, have a look to the article published in the just released special issue of Acque Sotterranee, Italian Journal of Groundwater. Comment very welcome.
Full article Access (external link): https://www.acquesotterranee.net/acque/article/view/751/538
Special issue: https://www.acquesotterranee.net/acque/issue/view/57 
recarga artificial
Managed Aquifer Recharge