(i) Whenever a tenancy in a dwelling unit terminates after the beginning, but before the end, of a billing period for which the landlord has not been billed by the water company, the landlord shall give to the tenant on the last day of such tenancy the reading on the submeter for the dwelling unit as of that day together with a final bill for water usage in the dwelling unit since the last prior reading of the submeter for such dwelling unit. The landlord shall charge the same rate for the water used by the tenant as the water company charged in the last bill issued to the landlord. Notwithstanding paragraph (f), the bill shall be immediately due and payable by the tenant. If the tenant does not pay the bill, the landlord may deduct the amount of the bill from any security deposit paid by the tenant in accordance with section 15B of chapter 186, prior to returning the balance of the security deposit, if any, to the tenant. If the landlord is not able to give the final reading on the submeter for the dwelling unit together with a final bill for water usage to the tenant on the last day of the tenancy, the landlord shall mail such reading and such final bill to the tenant no later than the day after the termination of the tenancy. If the water company subsequently charges the landlord a lesser rate than the landlord charged the tenant in the final bill, the landlord shall recalculate the bill forthwith based on the lesser rate and mail to the tenant the revised bill together with a rebate for any overpayment made by the tenant.