Hi, thanks for posting your concern in the HCM. 
My opinion is all the toxic metals including lead and mercury can cause 
impotence or 
erectile dysfunction. But, there is a threshold amount above which they are toxic for both chronic and acute ingestion.
Hence, very old pipes should be replaced at the earliest for public health safety.
Usually  the source of lead and copper is generally the customer-owned piping (bronze and brass faucets, copper pipe, solder). So special water sampling is needed. Also these pipes should be replaced by non-metal pipes.
Hope you are satisfied with my answer. If you think I have satisfactorily resolved your query, please rate my answer. If you have any further query related to this, please write back.
In case you have any new query in future, you can directly ask me questions @ http://www.HealthcareMagic.com/doctors/dr-kaushik-sarkar/68460. I will try my level best to help you.
Regards,
Dr. Kaushik