Pwani Decentralised Solar Desalination Network
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| Pwani Decentralised Solar Desalination Network (100 plants) | |
|---|---|
| Project | |
| Status | proposed |
| Theme | Water |
| Pillar | Infrastructure |
| Counties | Mombasa, Kwale, Kilifi, Tana River, Lamu, Taita-Taveta |
| Lead organisation | Pwani 2050 |
| Funding source | Not yet identified |
The Pwani Decentralised Solar Desalination Network is a project within the Water theme. It is a proposal from the Pwani 2050 plan to provide "fresh water for every citizen" on the Kenyan coast: municipal water would cover each town and up to 20 km beyond it, and about 100 small solar-powered desalination plants would put every other resident within 2 km of a plant. Small solar desalination units already run at several places on the coast, built by the charity GivePower, but each supplies tens of cubic metres a day, mainly as drinking water. A rough check on this page suggests that 100 plants could reach every resident only if they were much larger than any built so far, and that a network of today's units would be a drinking-water supplement rather than a full supply. A separate page covers EDIC's proposal for a single large private desalination plant for Mombasa.
What it is
The plan combines two ideas. Towns would extend piped municipal supply to a radius of 20 km around them, and in the gaps a network of about 100 decentralised plants, each powered by solar panels and drawing on seawater or brackish groundwater, would serve everyone within 2 km. The plan gives no size, cost, operator or timetable.
Existing solar desalination on the coast
The best-known example is GivePower's plant at Kiunga in Lamu County, near the Somali border, which went into service in 2018. Reports describe a reverse osmosis unit producing 50,000 to 75,000 litres a day from a 50 kW solar array with battery storage, built for about US$500,000 to 565,000 and run by local staff, with water sold through M-Pesa and repairs paid for from sales.[1][2] GivePower has since opened a plant with Mombasa County at Mishomoroni in Kisauni, announced in September 2023 at up to 75,000 litres a day,[3] and announced units at Mtwapa (up to 75,000 litres a day), Ukunda (up to 15,000 litres a day, for over 38,000 residents) and Chindi (up to 6,000 litres a day).[4][5][6] GivePower describes its plants as producing 10,000 to 75,000 litres a day, built for 20 years or more and run under partnerships in which water sales cover operation and repairs.[7]
Testing the concept
The figures below are calculated on this page from the cited sources and are order-of-magnitude estimates, not a design.
The six coastal counties had 4.33 million people on 82,383 km² in 2019, from Mombasa at 5,495 people per km² to Tana River at 8.[8] One hundred circles of 2 km radius cover about 1,257 km², or 1.5 per cent of that area, so the 2 km promise holds only where people live in about a hundred dense clusters, which is not the case in much of Tana River, Lamu, Kwale and Kilifi. The 20 km municipal zones would have to carry most of the population.
The water regulator counts 20 litres per person per day as the domestic minimum, and the national average actually consumed in 2023/24 was about 26 litres.[9] At those rates the whole coast would need about 87,000 to 113,000 m³ a day. Shared among 100 plants, that is about 870 to 1,130 m³ a day each, 12 to 15 times the largest GivePower unit of 75 m³. One hundred plants of today's largest size would make about 7,500 m³ a day, about 1.7 litres per coastal resident, enough for drinking but not for washing and cooking. Scaling Kiunga's cost of roughly US$7,000 to 11,000 per m³ of daily capacity to 87,000 m³ a day gives about US$0.6 to 1 billion before pipes, though larger plants would be cheaper per unit.
Rationale
Access to safe water on the coast is poor and uneven. In the 2019 census, 43.5 per cent of Mombasa households named a water vendor as their main source of drinking water, and in Kwale and Tana River about 40 per cent relied on ponds, dams, rivers or unprotected wells and springs.[10] The regulator notes that "Mombasa County lacks its own local water sources" and that the coast's bulk water system draws on Mzima Springs, Marere Springs, the Tiwi boreholes and the Baricho well field.[11] Many coastal wells are brackish: Kiunga residents drank salty water before their plant opened.[2] Small solar units suit places far from pipes and from the grid, and GivePower's Mishomoroni plant sells water at KSh 20 per 20 litres against KSh 30 to 50 from vendors.[12]
Status and timeline
The network exists only as a proposal in the Pwani 2050 plan. The small plants already running were built individually by GivePower with county and corporate partners; no county or national programme for a network of them has been announced. Kiunga was reported to have kept running through the COVID-19 restrictions,[2] but no recent report on its condition has been found.
How the project would be procured
There is no Terms of Reference, study or budget. Under the Water Act 2016, water services are provided by licensed water service providers, usually county-owned companies, so a network would most likely be run through the existing county utilities or under partnerships with them.[13]
Who is involved
The proposal comes from the Pwani 2050 plan. The county governments and their water companies, the Coast Water Works Development Agency and the Water Services Regulatory Board would be the main public bodies.[11] GivePower is the main operator of small solar desalination units on the coast.
Concerns and counterpoints
No one has commented in public on this proposal. The points below are the main concerns about small water systems and desalination, given as general context.
Keeping small systems working
Small rural water systems often break down. Researchers at Oxford's REACH programme estimate that about 30 per cent of handpumps in Africa are out of action at any time,[14] and in Kitui County they found that professional maintenance could lift piped-scheme functionality above 83 per cent, but that user fees covered only about 8 per cent of its cost.[15] A desalination unit has more parts that can fail than a handpump: membranes, pumps, batteries and inverters. A network of 100 plants would need a maintenance organisation and spare-parts supply across six counties.
Paying for it
The coast's water utilities are already under financial strain. The regulator reports that Lamu's utility covered only 40 per cent of its operating costs, that Tana's ranked second from bottom nationally, and that none of the coast's bulk water buyers had consistently paid for bulk supply.[16] Desalinated water at KSh 20 per 20 litres costs KSh 1,000 per m³, several times the piped tariff, so plants that cover their costs from sales would serve drinking needs better than full household supply.
Brine
Reverse osmosis returns concentrated brine to the sea: at Kiunga, about 6 litres of brine for every 2 litres of fresh water.[2] At that ratio, supplying the whole coast's needs would mean several hundred thousand cubic metres of brine a day (calculated on this page), discharged along a coast with marine parks and reserves such as Kiunga and Kisite-Mpunguti.
Alternatives
Rainwater is already the main source for many households in Lamu, about 10 per cent county-wide,[10] and larger schemes such as the Mwache Dam, the Mzima II pipeline and the Sabaki Water Carrier aim to serve the coastal towns. Decentralised plants would make most sense where these cannot reach.
Sources
- 2019 Kenya Population and Housing Census, Volume I, KNBS.
- 2019 Kenya Population and Housing Census, Volume IV, KNBS.
- Impact 17, WASREB, 2025.
- Solar Water Solutions, GivePower.
References
- ↑ Spaceship-Like Tesla Powerwall Setup Produces 50K Liters of Clean Water a Day, Mike Brown, Inverse, 10 July 2019.
- ↑ 2.0 2.1 2.2 2.3 Solar beats salt: bringing clean water to coastal Kenyans, Benson Rioba, Thomson Reuters Foundation, republished by GivePower, undated.
- ↑ GivePower and ServiceNow partner to bring safe, affordable drinking water to Mombasa County, Kenya, GivePower, 25 September 2023.
- ↑ GivePower opens 17th Solar Water Farm in Ukunda, Kenya, GivePower, undated.
- ↑ GivePower and ServiceNow partner to bring solar-powered desalination to Mtwapa, GivePower, undated.
- ↑ The ripple effect of one trek: how CAC brought safe water to Chindi, Kenya, GivePower, undated.
- ↑ Solar Water Solutions, GivePower, read 15 October 2026.
- ↑ 2019 Kenya Population and Housing Census, Volume I, Kenya National Bureau of Statistics, 2019, printed page 10 (Table 2.4).
- ↑ Impact 17: A Performance Report of Kenya's Water Services Sector 2023/24, Water Services Regulatory Board, June 2025, printed pages 23 and 99.
- ↑ 10.0 10.1 2019 Kenya Population and Housing Census, Volume IV, Kenya National Bureau of Statistics, 2019, printed page 300 (Table 2.15).
- ↑ 11.0 11.1 Impact 17, Water Services Regulatory Board, June 2025, printed page 91.
- ↑ GivePower and ServiceNow partner to bring safe, affordable drinking water to Mombasa County, GivePower, 25 September 2023.
- ↑ Water Act, 2016 (No. 43 of 2016), Kenya Law, consolidated to 31 December 2022.
- ↑ Can a rural handpump tell you it's not well?, Heloise Greeff, REACH, University of Oxford, 22 March 2016.
- ↑ Model results for scale-up of professionalized water services maintenance in Kenya, Pranav Chintalapati, REACH, 18 April 2023.
- ↑ Impact 17, Water Services Regulatory Board, June 2025, printed pages 40, 58 and 91.