Del. Code tit. 9 § 4521
Any annexation by any municipality of any previously unincorporated area shall not confer upon the annexing municipality any right, title or interest in any part of any water or sewer system constructed, acquired, extended or improved pursuant to this chapter, except as a resolution of the county government may so provide. No such resolution shall be adopted by the county government unless the annexing municipality shall have deposited a fund sufficient to pay when due any outstanding bonds issued hereunder for the purchase, construction, acquisition, extension or improvement of all systems wholly or partly within the annexed area, with interest to the date of call or redemption and any redemption or call premium applicable thereto.
9 Del. C. § 4521