(a) The board shall contract for construction and repair and renovation of district facilities and for the purchase of equipment, materials, machinery, and all things that constitute or will constitute the plant, works, facilities, or improvements of the district in accordance with this section. The bidding documents, plans, specifications, and other data needed to bid on the project must be available at the time of the first advertisement and the advertisement shall state the location at which these documents may be reviewed.
(b) A contract may cover all the work to be provided for the district or the various elements of the work may be segregated for the purpose of receiving bids and awarding contracts. A contract may provide that the work will be completed in stages over a period of years.

(c) A contract may provide for the payment of a total sum that is the completed cost of the work or may be based on bids to cover cost of units of the various elements entering into the work as estimated and approximately specified by the district’s engineers, or a contract may be let and awarded in any other form or composite of forms and to any responsible person or persons that, in the board’s judgment, will be most advantageous to the district and result in the best and most economical completion of the district’s proposed plants, improvements, facilities, works, equipment, and appliances.
(d) For contracts over $150,000, the board shall advertise the letting of the contract, including the general conditions, time, and place of opening of sealed bids. The notice must be published in one or more newspapers circulated in each county in which the district is located. If there are more than four counties in the district, notice may be published in any newspaper with general circulation in the district. The notice must be published once a week for two consecutive weeks before the date that the bids are opened, and the first publication must be not later than the 14th day before the date of the opening of the sealed bids.
(e) For contracts over $25,000 but not more than $150,000, the board shall solicit written competitive bids on uniform written specifications from at least three bidders.
(f) For contracts of not more than $25,000, the board is not required to advertise or seek competitive bids.
(g) The board may not subdivide work to avoid the advertising requirements specified in this section.
(h) The board may not accept bids that include substituted items unless the substituted items were included in the original bid proposal and all bidders had the opportunity to bid on the substituted items or unless notice is given to all bidders at a mandatory pre-bid conference.
(i) If changes in plans, specifications, or scope of work are necessary or beneficial to the district, as determined by the board, after the performance of the contract is begun, or if it is necessary or beneficial to the district, as determined by the board, to decrease or increase the quantity of the work to be performed or of the materials, equipment, or supplies to be furnished, the board may approve change orders making the changes. The board may grant authority to an official or employee responsible for purchasing or for administering a contract to approve a change order that involves an increase or decrease of $150,000 or less. The aggregate of the change orders that increase the original contract price by more than 25 percent may be issued only as a result of unanticipated conditions encountered during construction, repair, or renovation or changes in regulatory criteria or to facilitate project coordination with other political entities. A change order is not subject to the requirements of Subsection (d) or (e).
(j) The board is not required to advertise or seek competitive bids for the repair of district facilities if the scope or extent of the repair work cannot be readily ascertained or if the nature of the repair work does not readily lend itself to competitive bidding.
(k) The board may use the reverse auction procedure, as defined by § 2155.062(d), Government Code, for purchasing.
(l) The board is not required to advertise or seek competitive bids for security or surveillance systems or components of or additions to district facilities relating to security or surveillance, including systems used for the prevention of terrorist or criminal acts and incidents or acts of war, if the board finds that doing so would compromise the safety and security of district facilities or residents.
(m) In accordance with this section, the board of a district created by special law may elect to contract for the construction and repair and renovation of district facilities and for the purchase of equipment, materials, machinery, and all things that constitute or will constitute the plant, works, facilities, or improvements of the district, notwithstanding a conflicting provision in the district’s special law. For such a district, an election under this subsection must be by resolution of the board and applies only to a contract entered into on or after the effective date of the resolution.