**1. Introduction**

The increase in the population of an area will have an impact on the demand for clean water supply. When the demand for water supply exceeds the capacity, it will lead to a water crisis because the need for water is not only for domestic use but also for various human activities such as industry and agriculture. The main source of water to meet human demand comes from surface water sources such as rivers, ponds and lakes. However, due to increasing demand for water resources, the groundwater resources have been explored on a large scale, especially for drinking water supply [1–4].

The current trend of using groundwater resources as a domestic water supply for humans is no longer uncommon. Polluted river water resources have led the

residents or responsible authorities in providing water supply to opt for groundwater resources [5, 6]. Obtaining groundwater resources may not be an obstacle in the plain or continental areas but this situation is slightly exacerbated in island areas. However, groundwater resources are susceptible to water pollution that resulted from human activities such as domestic waste disposal and industrial activities [7]. The main cause of groundwater pollution is due to the disposal of sewage waste from tourism activities, agriculture and residential settlement in an island area [5, 8–10] and at the same time also resulted from natural factors such as the encroachment of saltwater on groundwater or wells nearby the area [11–13].

Groundwater is generally a source of water that is clean and can be easily accessed by building a well and by using pipes and channeling it into the reservoirs. In this case, the lack of freshwater resources particularly in the island area has urged the residents living in the area to have to use this water resource. Therefore, these water resources are specifically for domestic use such as drinking water supply, cooking, bathing and washing. This situation is increasingly affected when the island has been turned into a tourist destination causing the demand for water supply to increase. Therefore, the status of this groundwater quality should also be given special attention so that it is safe to be used by tourists and the local community [7, 8, 14, 15].

Kapas Island in Marang, Terengganu is a less populated area due to its small land area, which is the case with other islands. However, this island has its own charm due to the beauty of its beaches, unpolluted sea and a fascinating marine park. However, the lack of surface water resources such as river water has led local people and operators of resort and chalet for tourism activities to use groundwater resources as the main source of domestic water supply. The major issue is that the condition of these groundwater resources are sometimes unclean, murky and suspended solids are found when channeled to tourist accommodations. Therefore, the purpose of this study is to analyze the quality of groundwater supplied by accommodation operators in Kapas Island to tourists and local residents by using the Water Quality Index (WQI) as set by the Department of Environment (DOE) Malaysia.
