Phuket, Water Security and Management
Freshwater availability represents one of the most critical ecological limits to growth for Phuket. The island operates under severe seasonal hydrological stress, where peak demand from international tourism coincides precisely with the dry period of minimal rainfall.
—
## 8.1 Hydrological Profile and Raw Water Supply
Phuket relies primarily on surface water captured in three main public reservoirs managed by the Royal Irrigation Department (RID) and supplying the Provincial Waterworks Authority (PWA):
* **Bang Wad Reservoir (Kathu District):** Capacity of ~10.2 million cubic metres ($m^3$).
* **Bang Neow Dam (Thalang District):** Capacity of ~12.6 million $m^3$.
* **Klong Kata Reservoir (Mueang Phuket District):** Capacity of ~4.3 million $m^3$.
Combined public reservoir storage capacity totals approximately **27.1 million $m^3$**. In addition to surface reservoirs, water is sourced from private abandoned tin mine pits (*kbuang*), deep groundwater wells, and limited commercial desalination units operated independently by luxury resort properties.
—
## 8.2 Demand Dynamics: Resident Baseline vs. Tourism Multiplier
Water consumption on the island exhibits extreme variance between resident and visitor user groups:
“`
┌─────────────────────────────────────────────────────────────────────────┐
│ PER CAPITA DAILY WATER CONSUMPTION │
└─────────────────────────────────────────────────────────────────────────┘
Local Resident Baseline: ██████ 200–250 Litres/day
Standard Visitor Average: ████████████ 400–500 Litres/day
Luxury Resort Visitor: █████████████████████████ 1,000–1,500+ Litres/day
“`
* **Seasonal Demand Peak:** During the dry high season (December–April), daily island water consumption spikes significantly. The arrival of over 1 million monthly tourists coincides with high evaporative losses and minimal rainfall, depleting public reservoirs to critical operating thresholds.
* **Inter-Sectoral Competition:** When surface reservoirs drop below 30% capacity during extended dry spells, municipal water distribution to local residential neighbourhoods is frequently throttled or rationed, while commercial hospitality operations purchase private water trucked from inland mine pits at high economic cost.
—
## 8.3 Wastewater Generation, Infrastructure, and Receiving Waters
Freshwater consumption directly generates massive volumes of municipal wastewater. Infrastructure capacity has consistently failed to keep pace with rapid accommodation expansion:
| Parameter | Estimated Value | Source / Benchmark |
| — | — | — |
| **Daily Wastewater Generation (Peak)** | ~160,000–180,000 $m^3$/day | Pollution Control Department (PCD) |
| **Centralised Treatment Capacity** | ~65,000–75,000 $m^3$/day (Across 5 main plants) | Phuket PAO / Municipal Services |
| **Island-Wide Treatment Rate** | **~38–42%** of total generated volume | PCD State of Environment Audits |
| **Primary Discharge Destinations** | Coastal streams, estuaries, and nearshore marine waters | Environmental field surveys |
Un-sewered coastal zones rely on localized septic tanks or basic absorption pits, which perform poorly in low-lying coastal soils with high water tables. As a result, large volumes of partially treated or raw effluent containing high loads of nitrogen, phosphorus, and organic matter discharge into shallow bays (notably Patong, Kata, and Rawai), driving coastal eutrophication and coral reef degradation.
—
> ### CASE STUDY 2: Seasonal Water Scarcity and Inter-Sectoral Competition Between Tourism and Municipal Demand
>
>
> **Location:** Kathu and Mueang Phuket Districts
> **Primary Issues:** Seasonal reservoir depletion, severe water supply rationing, high commercial water prices, and social tension.
> **Overview & Context:**
> During the extended dry season of early 2019 (and recurrent dry spells), surface water storage in the Bang Wad and Bang Neow Dam reservoirs dropped below critical operational thresholds. The convergence of high-season tourist arrivals with dry monsoon conditions created a severe water deficit across the central and southern districts.
> **Key Dynamics Observed:**
> * **Municipal Rationing:** The Provincial Waterworks Authority (PWA) was forced to reduce water pressure and implement intermittent supply schedules for local residential communities to stretch remaining reservoir reserves.
> * **Commercial Supply Substitution:** Large resort hotels bypassed public supply shortfalls by purchasing raw water delivered via private tanker trucks from private abandoned tin mine pits (*kbuang*). This drove up resort operational costs while depleting unmonitored inland groundwater storage.
> * **Social Frictions:** Local resident communities expressed rising dissatisfaction over perceived priority given to tourism zones during water shortages, highlighting the direct link between water security and destination social license.
>
>
> **Evidence-Based Outcomes & Governance Response:**
> The crisis accelerated plans for regional water diversion pipes from mainland Phang Nga Province and expanded raw water extraction from private tin mine pits. However, structural supply constraints remain, proving that continuing accommodation growth without parallel raw water storage expansion and greywater recycling creates extreme vulnerability to seasonal climate shocks.