An alternative to reallocate water rights among users is through a market pricing mechanisms (SIWI, 2016), better known as “Water Trading”, defined as “the voluntary buying and selling of water in some quantifiable form; either in the present or future” (Wheeler et al., 2017, 22). Water trading can exist for groundwater and surface water markets. It can take place through informal arrangements between users (e.g., neighbouring farmers) or formal arrangements (water markets governed by standardised rules and processes through governments or communities). Additionally, it is possible to classify water trading into three types (Wheeler and Garrick, 2020):
- Water allocation trade: Short-term or temporary transfers of water that is already allocated and available for immediate use.
- Water leasing: Medium-term leasing of water allocations in a manner that enables a water user to plan secure access to water for a period of time specified in a contract.
- Water entitlement trading: Permanent transfers of water entitlements (property rights), specifying either a proportion or fixed quantity of the available water at a given source.