(a) Each rural water company shall maintain a roster of all members which shall include the date upon which each member joined.
(b) Each rural water company shall maintain a roster of patrons which shall include periodic data as to services rendered by the water company. Such roster shall be the basis for any distribution of excess revenues of the water company. Any such distribution shall be to the members and shall be based upon patronage for the time period over which such excess revenues to be distributed were collected, and the loss of membership by death or otherwise shall not terminate the rights and interest of such member in any patronage distribution due him at the termination of his membership. Any amount to be distributed shall be net income or funds in excess of those needed to meet current losses and operating expenses; provided, that such amount to be distributed shall be in excess of that needed for normal, reasonable business purposes.