D.C. Code § 34-2405.04
Assessments for water mains and service sewers shall be payable in 3 equal installments, the 1st of which shall be due and payable without interest within 30 days from date of service of notice or of the last publication of notice as the case may be, the second within 1 year, and the third within 2 years from the date of assessment, and interest at the rate of 6% per annum shall be charged on all amounts which shall remain unpaid at the expiration of 30 days from the date of service of notice or last publication as the case may be; but the owner of the property assessed may, at his option, at any time after the levying of such assessment, pay the same in full; provided, that if any installment of any assessment for water main or service sewer levied under the provisions of this subchapter shall not be paid when due and payable the property against which said assessment was levied may be sold for said delinquent installment at the next ensuing annual tax sale in the same manner and under the same conditions as property sold for delinquent general taxes, if said installment shall not have been paid prior to said sale.
D.C. Code § 34-2405.04