HOUSTON, April 29 (UPI) - A Houston man said a clerical error led to a $99,000 check he made out to a Dallas securities firm being used to pay a water bill for the next 600 years.Don Mathis said he mailed the check, which was meant to purchase a certificate of deposit, directly after paying his granddaughter's water bill, $13.74, by phone, the Houston Chronicle reported Tuesday.However, the check instead arrived at Houston's Department of Public Works and Engineering office and it was processed, endorsed and deposited automatically."Mr. Mathis mailed a check payable to Southwest Securities, which was processed through our automatic payments processing system," "Due to the high volume of checks received daily, we did not notice the mistake." Houston public works Director Michael Marcotte said in a memo to the City Council.The City Council is expected to vote Wednesday to approve a refund for Mathis.