Integrating wastewater reuse into water management schemes of Caribbean SIDS: A Trinidad and Tobago case study

Wastewater presents a risk of fluvial, lacustrine, and edaphic pollution to urban and rural environments (Rojas-Valencia et al., 2011). Guerra-Rodríguez et al. (2020) noted that current technologies to recover nutrients from wastewater have not reached their full potential. Poor wastewater management practices also have debilitating effects on coastal ecosystems which are vital socio-economic resources (Scalley, 2012). Naidoo & Olaniran (2014) added that minimizing the discharge of wastewater into aquatic environments can maintain the oxygen content and water and energy cycles for organisms that inhabit these ecosystems. Globally, water resources are under pressure due to economic growth and development, population growth, urbanization, industrialization and agricultural activities and more recently climate variability and change (Mishra, 2023). As urban water shortages worsen and water purification technology develops, wastewater is increasingly being recovered in larger quantities and for more diverse purposes (Asano & Levine, 2004). Wastewater reuse, also known as water recycling or water reclamation, involves treating and repurposing wastewater for various applications such as irrigation, industrial processes, environmental restoration, and with advanced wastewater treatment systems, for potable use. In recognition of the potential benefits of wastewater reuse and in attempts to address water scarcity and ensure sustainable water management practices; international organizations, governments, and water management bodies have been actively working towards establishing common policies and guidelines.

The United States developed the largest number of water reuse projects of any country, supported by policies and regulations that promote safe reuse of water from recycled wastewater. In 2017, 14 states had policies to address indirect potable reuse and three to address direct potable reuse, compared with eight and none, respectively, in 2012 (Tortajada, 2020). California is the most progressive state regarding indirect potable water reuse. It has the most developed regulatory frameworks. For more than 50 years, several cities have implemented planned replenishment of groundwater basins with reused water. Regulations were adopted in 1978 and revised in 2014. Indirect potable reuse regulations of surface water augmentation were adopted in 2018. They allow treated/reclaimed water to be discharged to surface water reservoirs which are used as sources of drinking water (Tortajada, 2020). Reused water has also been used in countries such as Namibia and Singapore. Windhoek, Namibia began direct potable reuse 55 years ago to manage droughts and water scarcity (Van Rensburg, 2016). Singapore began treating wastewater for reuse, called ‘NEWater’, two decades ago to boost sustainability (Tortajada, 2020). NEWater accounts for two-fifths of daily water consumption and this is expected to grow by 15% in the next four decades (Tortajada, 2020). Williams (2016) illustrated that Singapore's water management portfolio includes industrial reuse of almost one third of its supply. Wastewater forms part of the flow of the Seine River which is treated and fed into the aquifer that supplies drinking water in France (Binnie & Kimber, 2008). Additionally, Israel demonstrated the use of reclaimed municipal wastewater in agriculture and groundwater recharge (Peters, 2015). Technology and private sector participation emerged as essential to guarantee the socio-economic and environmental merits in a pilot study in Athens, Greece (Gude, 2017). Well-developed technologies for irrigation in agriculture and landscaping have been noted in countries such as Bahrain where chlorine is used for disinfection while ultraviolet radiation is used in Kuwait, Tunisia, and the United Arab Emirates (Binnie & Kimber, 2008). Maturation ponds are used in Morocco while ozonation is used in Saudi Arabia. Waste stabilization ponds (WSPs) and aerated lagoons are used in Jordan and Tunisia (Binnie & Kimber, 2008). Kihila et al. (2014) noted that WSPs effectively eliminate contaminants. Bartone & Arlosoroff (1987) determined that WSPs are affordable and eliminate odour. Libhaber & Orozco-Jaramillo (2013) documented other methods of wastewater treatment such as rotational microscreens, vortex grit chambers, anaerobic, facultative and polishing lagoons, up-flow anaerobic sludge blanket reactors, anaerobic filters, piston anaerobic reactors, anaerobic baffled reactors, and activated sludge.

Climate change is posing a growing threat to the Caribbean region, with one of its most concerning impacts being the significant reduction in rainfall and the subsequent decline in available water sources. Rising global temperatures and changing weather patterns are contributing to prolonged droughts and altered precipitation patterns across the Caribbean islands (Roopnarine et al., 2021). These shifts disrupt the delicate balance of freshwater availability, exacerbating water scarcity issues. As less rainfall replenishes freshwater reservoirs and aquifers, the region faces a critical challenge in maintaining a stable and reliable water supply, putting both ecosystems and the livelihoods of local communities at risk. Co-occurring disasters have also impacted the water sector as seen with COVID-19 and the volcanic eruption in St. Vincent and the Grenadines (Roopnarine et al., 2023).

Ault (2016) highlighted the need for long-term policies that cater for future changes in climate to manage water for food production and public use. Access to freshwater in the Caribbean is variable among islands. Geomorphology largely influences supply. Retention is subject to factors such as topography and size (Scalley, 2012). Ahmad (2015) documented an increased demand for water as temperatures rise. Scalley (2012) listed Trinidad and Tobago among islands in the Caribbean where rural inhabitants lack reliable access to water. Ekwue (2010) documented an unreliable supply in Guyana. Gude (2017) determined that the region faced economic water scarcity which required means to access available sources and listed contamination of surface storage and reliance on one source among factors that contribute to shortages. Dependable access to a sufficient supply is a pillar of water security (Amadio et al., 2014). Ekwue (2010) noted high per capita consumption in Trinidad and Tobago, Barbados, and The Bahamas. Jones et al. (2021) recognized a combination of influences on wastewater reuse for which data are required. Cashman (2011) highlighted the socio-economic importance of water. Nations like Saint Lucia and Saint Kitts and Nevis lack the resources to support irrigation while Trinidad and Tobago can irrigate more land with greater access to water (Ekwue, 2010). Ekwue (2010) documented Antigua and Barbuda as a water-scarce nation with high water stress.

Some Caribbean islands are low-lying and do not have perennial streams such as Antigua and Barbuda and Barbados. Alternative solutions such as desalination have demonstrated stark economic and environmental implications (Scalley, 2012). Scalley (2012) found wastewater reuse as an integral part of the management of water resources in the Caribbean. The treatment and reuse of rainwater is considered one of the two main resolutions to challenges of water availability and suitable for Small Island Developing States (SIDS) which have limited surface (Tota-Maharaj & Paul, 2015). Gleick & Cooley (2021) suggested that reusing treated wastewater is both cost-effective and innocuous to the environment. Treatment reduces contamination below quality thresholds which vary by sector for the purpose of reuse (Jones et al., 2021). In the Caribbean, a critical reason that wastewater reuse is gaining momentum is because there is an increasing demand for potable water across different sectors such as tourism and overall domestic needs. In Barbados, recycled water is mainly used for landscaping purposes in the tourism industry (Peters, 2015). Conversely, in Antigua and Barbuda wastewater is reused for irrigation which is similar to the application in Jamaica, and St. Kitts and Nevis where water is reused for golf courses (Peters, 2015). The Government of Grenada recognized the potential for integrated water resources management on the island in their roadmap developed in 2007 but reuse practices were limited to the household at the time of the study (Peters 2015). Similarly, wastewater reuse in St. Vincent is limited to domestic reuse for applications such as backyard gardening. On the other hand, 39% of the resorts in the Grenadines, according to George et al. (2007), used treated wastewater similar to Anguilla where all hotels practice some applications of wastewater reuse in the absence of municipal wastewater reuse. Overall, Antigua and Barbuda and St. Vincent have the highest percentage of municipal wastewater being reused however in both cases it is still below 10% (Peters, 2015). Janson et al. (2021) noted that for many Caribbean islands precise figures on treated wastewater is not available. There have been significant efforts around the region however, particularly in Trinidad and Tobago and Jamaica to increase the coverage of existing centralized wastewater treatment plants as well as efforts to establish new facilities.

Although wastewater reuse is not prevalent in Trinidad and Tobago, several broad policies relevant to wastewater reuse exist in the country. Vision 2030: The National Development Strategy of Trinidad and Tobago 2016–2030 includes the implementation of water pollution and wastewater management programmes and regulations as a strategic initiative in achieving the country's environmental goals (GoRTT, 2016). Priority 2 of the National Environment Policy (GoRTT, 2018) also aims to ‘encourage water conservation through recycling and wastewater reuse…’. Of added importance is that the Environmental Management Act, Chapter 35:05 (GoRTT, 2001), legislates achieving and maintaining the goals of the NEP 2018 (GoRTT, 2001). The Water Pollution Rules (GoRTT, 2019) also require standards to be met in order to discharge effluent into various aquatic environments. More specifically, in 2022, the Government of Trinidad and Tobago approved the National Integrated Water Resource Management Policy, which states that the Government will ‘promote the actual provision of water and wastewater services with the participation of communities and the private sector’, wherever practicable (GoRTT, 2022).

Despite this, the legislative and policy framework for Trinidad and Tobago does not speak explicitly to the use of wastewater for various applications, such as agriculture. Hence, the Trinidad and Tobago Bureau of Standards (TTBS) in collaboration with the Ministry of Public Utilities (MPU) and a group of stakeholders from various governmental and non-governmental organizations, created a standard for wastewater reuse in 2022, entitled ‘Wastewater Reuse – Agricultural and Other Applications’ (TTS 664:2022). This endeavour was a component of the Global Environment Facility (GEF) Caribbean Regional Fund for Wastewater Management (CReW+) project, ‘An Integrated Approach to Water and Wastewater Management Using Innovative Solutions and Promoting Financing Mechanisms in the Wider Caribbean Region.’ Therefore, treated wastewater (from domestic sources) that complies with TTS 664:2022 is safe for the purposes listed in the standard, such as irrigation of different types of crops (including those intended for raw consumption), irrigation of green spaces, and washing of animal enclosures (TTBS, 2022).

The reuse of wastewater for agricultural purposes is not foreign to the agricultural stakeholders of Trinidad and Tobago, mainly in the districts of Caroni and Maloney, where unregulated wastewater reuse in agriculture occurs (Warrick & Ekwue, 2014). This unregulated use, which may be unintentional, occurs due to the discharge of treated effluent from wastewater treatment plants into rivers. There are about 250 wastewater facilities in Trinidad and Tobago (T&T), according to the Wastewater Condition Assessment Report by GENIVAR (2007). About 30% of the population is connected to sewerage systems, while the remaining 70% of the population is served by septic tanks and pit latrines. The Water and Sewerage Authority (WASA) provides direct service to about two-thirds of the sewered population. According to the report, 70% of the current facilities are small-scale wastewater treatment facilities that are poorly maintained, have reached the end of their useful lives, or have been abandoned by private developers, causing the discharge of poorly treated sewage into the environment.

Public perception for pro-environmental initiatives such as wastewater reuse is critical for successful implementation. Peters & Goberdhan (2016) found through a survey that although the public in Trinidad was not comfortable with direct reuse of wastewater, most persons accepted the use of wastewater for non-potable purposes like irrigation of public lawns. The study indicated that the perceptions of wastewater were influenced by public mistrust of the local water authority, lack of knowledge of the treatment process; and perceived health risks associated with using treated wastewater. Conversely, Martin & Alexander (2014) found that support for wastewater reuse varied significantly when overlaid with various factors, including age, gender, education, income, and area of residence. This research paper examines the Knowledge, Attitudes, and Practices (KAP) as well as Willingness to Pay (WTP) and Barriers to Reuse of treated wastewater in Trinidad and Tobago.

Qualitative and quantitative data were collected from 145 respondents across Trinidad and Tobago via convenience sampling. Specifically, aKAP survey was deployed in July 2022 to gather stakeholders' understanding about treated wastewater, their attitudes towards its reuse and current practices. The target audience for the survey was stakeholders who would be able to utilize or contribute to the utilization of treated wastewater in the ways outlined by the standard. This therefore included technocrats/academics in the wastewater field, landscapers, hotel owners/recreational facility personnel, and farmers. The questionnaire was drafted by the MPU and then revised using feedback from the WASA, the University of West Indies (UWI), Trinidad and TTBS and other relevant stakeholders, including farmers. A pilot survey was launched within the MPU on July 14, 2022, and feedback was used to finalize the questionnaire. The final questionnaire consisted of 22 questions in total, split into four sections; demographics, KAP. The questions in the knowledge and attitudes section targeted all respondents, while those in the practices section were directed primarily towards farmers and other agricultural entrepreneurs or home gardeners.

The finalized questionnaire was disseminated online via Google Forms from July 21, 2022 to August 21, 2022, and physically at the Caribbean Community's (CARICOM's) Second Agri Investment Forum and Expo on August 19–21, 2022. Physical distribution was facilitated by the Agricultural Society of Trinidad and Tobago (ASTT). To improve accessibility to persons who could not read, the questions were read aloud while administering the survey.

The data gathered from the survey were subjected to both descriptive and inferential statistical assessment in the Statistical Package for Social Sciences (SPSS v19). Data were collated based on demographic attributes (age, gender, region (North, Central, South and Tobago)), KAP, WAP, and Barriers to Wastewater Reuse. All multiple response questions were disaggregated and then combined using the define variables function in SPSS. All data were coded dichotomously to allow for quantitative statistical analysis. KAP questions were combined, totalled, and categorized into poor and good (Table 1). Cross-tabulation, χ², and ANOVA were conducted using knowledge categories, attitude categories and practices categories against all demographic data to identify any existing relationships.

Respondents with tertiary education comprised 82.8% of the participants while 17.2% had secondary education. These results differed from the agriculture census of 2004 which reflected that the highest level of education of 27.90% of private agricultural holders was secondary and that of 2.09% was tertiary. Education among the participants reflected similarity to the sample surveyed by Peters & Goberdhan (2016).

Consistent with the agriculture census of 2004 which indicated that 94.9% of private agricultural holders were from Trinidad, the majority (84.8%) of respondents in the sample population were also located in Trinidad. Participants from northern areas of Trinidad accounted for 42.1% of respondents while 28.3% were from the central areas. Respondents from southern areas of Trinidad comprised 15.2% of the participants while 14.5% of respondents were from Tobago (Table 2). Virjee & Gaskin (2010) sampled a larger survey population and found that the respondents who relied on public water supply were distributed in these regions. This classification presents a clearer representation of the national distribution of the sample population than previous local studies which used delineations that do not engender immediate universal spatial understanding (Martin & Alexander, 2014). The Environmental Management Authority (1998) documented the largest surface storage in the northwest. The CIA (2023) noted that 53.4% of the population lives in urban areas. The capital city, located in the northwest, is home to 38.7% of the population.

Willingness to use treated wastewater existed among 84.1% of respondents. There was refusal among 4% while 11.9% remained unsure if they would be willing to use treated wastewater (Table 3). These findings support the influence of education identified by Tsagarakis & Georgantzis (2003). These results contrast to Massoud et al. (2018) which had a similar age demographic but a larger sample size and a gender disparity favouring women.

Religion was a deciding factor for 2.3% of participants while 7% indicated that they would not reuse wastewater because of their personal preference (Figure 5). These responses represent controlled factors that do not appear to pose a significant challenge to policy development. Chfadi et al. (2021) also found that religion was not a dominant influence on willingness to reuse wastewater. However, the opposite was supported by the findings of Massoud et al. (2018). This suggests a need for communal considerations in the national context which may pose a challenge to the capacity of Trinidad and Tobago as a small island nation. It further indicates a particular factor around which public awareness and education campaigns should include. Emphasis should be placed on strategies that build favourable receipt of this information. Other reasons posed a barrier for 3% of respondents. These responses accord with previous findings that support a hypothesis on trends of public perception towards wastewater reuse (Kelly & Morar, 2014).

Results of the χ² and ANOVA revealed no statistically significant (P > 0.05) relationships between frequency and means for KAP, WAP and Barriers to Wastewater Reuse against demographic factors (Table 4). This is consistent with the findings of previous studies (Miller & Buys, 2008). In contrast, Msaki et al. (2022) suggested the need for public education to facilitate implementation of wastewater reuse following findings of demographic influence in perceptions. It can be argued that a lack of significance may indicate the absence of bias, but it flags a need to further investigate the reasoning behind the responses. This study built on the previous local study by Peters & Goberdhan (2016) by investigating additional factors and highlighting a need for strategic engagement and education campaigns.

Concerns regarding wastewater reuse primarily revolve around the potential for inadequate treatment processes and the presence of contaminants. Once the necessary measures are effectively employed to ensure there are no impacts on human health, the use of treated wastewater can serve as an effective means of supplementing supply primarily for non-potable use but also with some potential potable use. While traditional remediation methods are expensive there are emerging technologies that are less labour intensive and costly that could be adopted across the region. Some countries, like Trinidad and Tobago have made significant investments in wastewater treatment plants, and therefore it would be prudent to extend the efforts to facilitate recovery and reuse through planned investment in treatment upgrades. There are clearly opportunities for beneficial reuse and the potential to supplement existing supplies.

The findings of this paper demonstrate the need for increased public awareness and capacity building as it relates to WWRU in Trinidad and Tobago as it can serve as effective means of supplementing supply for non-domestic uses. It also identified the major barriers to WWRU and therefore facilitates the development of targeted interventions. To promote the necessary culture change with respect to WWRU, capacity building and awareness raising strategies can be incorporated into and linked with existing water conservation campaigns. Given the potential for increased water scarcity associated with climate change and variability, it is crucial that Caribbean SIDS seek to identify and integrate alternative sources of water. Generally, there is a need to shift attitudes, perceptions and practices as the country attempts to incorporate WWRU as a national resource option. Considering the barriers identified and the willingness to pay and willingness to use, a strategic approach that considers mechanisms to address barriers, particularly health concerns and access to appropriately priced treated wastewater, can lead to increasing uptake on a national scale. This study can inform actions across the region and serve as a baseline to guide demonstration pilots which can determine implementation feasibility.

One key limitation of this study was the sample size. However, spatial coverage across both islands was achieved and the target was mainly persons who had interest in utilizing treated wastewater for agricultural and landscaping purposes. Responses were also voluntary and subject to self-report and recall bias. A similar study soliciting respondents from the general population may prove useful to gain an understanding from the complete spectrum of water users. Demonstration pilots furnished with monitoring assessment components are also recommended. Quantitative studies that outline precise demand and supply information on a sectoral basis would also be useful to inform the extent to which treated wastewater can supplement traditional supply.

Data cannot be made publicly available; readers should contact the corresponding author for details.

The authors declare there is no conflict.