Some Johns Island residents will see their sewer bills rise in July, and others will see them fall, because Charleston Water System has changed the way it will charge about 1,200 customers.

The change will apply only to those who get water service from St. Johns Island Water Co. and residential sewer service from Charleston Water System. Johns Island residents who get their water from wells will see no rate change.

Currently, Charleston Water System charges a flat sewer rate of $39.85 a month for St. Johns Island Water Co. customers who live within the Charleston city limits on Johns Island, and $55.25 for those outside the city limits.

Starting in July, Charleston Water System will charge those customers for sewer service based upon water consumption, as it does in the other areas it serves.

A flat rate was previously used due to a lack of data on St. Johns Water Co. customers' consumption. Customers who use more than 4,488 gallons of water monthly will see their sewer bills rise. Those who use less, roughly half the customers, will pay less than before.

Monthly bills will range from a minimum of $23 to a maximum of $110.98 for those within the city limits, and from $32 to $153.40 outside the city limits.

The maximum charge would apply to a customer using at least 13,464 gallons of water in a month.