A January 2026 report by the United Nations University cautions that Earth has entered an era of ‘global water bankruptcy’, where demand will consistently exceed available supply. 

In Kenya, water scarcity is a challenge. The current per capita freshwater availability (amount of water available per person per year) is 527m³, below the global benchmark of 1000m³ as per the Falkenmark Water Stress Indicator.  Current projections indicate that this figure could decline to approximately 475 m³ by 2030. Population growth, poor management, and climate change are the main causes.

Kenya continues to feel the effects of climate change, experiencing increased drought frequency and intensity and reduced access to reliable freshwater. Consequently, more households, businesses, and institutions are adopting rainwater harvesting systems to supplement traditional water sources. This way, you could secure year-round water availability for domestic, agricultural,  and commercial use. Methods such as roof catchments, rock catchments, sand dams, and rubber check dams are common.

Kenya Rainwater Harvesting Regulations

Kenya regulates water harvesting under the Water Act, 2016 , the Water (Amendment) Act, 2024, and subsidiary regulations like the Water (Harvesting and Storage) Regulations 2025 (Legal Notice 57 of 2025).

These laws create a national framework for water harvesting and storage, applying to all public and private water works.

With these laws, the government aims to integrate water harvesting into Kenya’s national water resource planning. Hopefully, our country will have better flood control, drought resilience, and climate change adaptation.

Rainwater Harvesting Requirements According to the Rainwater Harvesting Regulations

The law sets clear guidelines for roof-based, land-based, and agricultural rainwater harvesting in Kenya. Water Act, 2016, empowers the Cabinet Secretary to make regulations guiding rainwater harvesting and household water storage in Kenya (Section 142, 2J).

Under the 2025 water harvesting and storage regulations:

•       Any building constructed after March 6 2025 (when these regulations commenced), to be used as an institution, place of employment, manufacturing area, industry, commercial establishment, or a place to serve customers, must adequately fit gutters to catch rainwater or have ground catchment (Section 51, 1). These tanks must be capable of holding rainwater sufficient for the building’s water needs for at least seven (7) days (Section 51,2).
•       Should it be difficult to install gutters, provide ground catchment, or provide tanks of the capacity described in point 1, the county government or water services provider MAY supply drinking water from a piped supply.
•       A county government may allow a building owner or occupier to fully or partly comply with the above two (2) regulations, subject to any conditions or restrictions it considers appropriate.

Guidelines for Roof-based Rainwater Harvesting 

Here’s what to do when harvesting rainwater via a rooftop.

According to the Water (Harvesting and Storage) Regulations, 2025, how to use harvested rainwater depends entirely on whether the water is designated for non-potable (e.g., irrigation, cleaning, and flushing toilets) or potable (drinking and cooking) use.

Use a filter at the storage tank’s inlet. Standard filtration, e.g., using standard physical filters such as first-flush diverters, silt traps, or sand-gravel filters, is required for non-portable uses.

For uses like drinking, cooking, and food preparation, it’s best to treat harvested rainwater via methods like boiling, chlorination, and UV filtration. Article 43 of the Kenyan Constitution guarantees every person the right to clean and safe water in adequate quantities, and the Public Health Act (Cap. 242) directs property owners and landlords to provide safe, clean water. Therefore, if you’re supplying rainwater, ensure that it’s fully treated, in line with the drinking water guidelines set by the Water Services Regulatory Board (WASREB).

Direct surplus water available after filling a storage tank to an open well through a recharge structure or pits. To recharge an open well or borehole, harvest rainwater through artificial structures or pits, irrespective of the nature of subsoil conditions. However, the water must meet the Water Resources Authority’s (WRA) water quality standards.  

This is a highly regulated practice requiring prior authorization from WRA. You’ll need a licensed hydrogeologist to submit a design for the recharge structures and water treatment mechanisms. The water must be tested and analyzed at certified WRA Laboratory Services facilities to ensure it doesn’t pose any contamination risk and that it matches the existing aquifer’s chemistry.

Rainwater harvesting for tiled, sloped, or flat roofs.

If you’re harvesting rainwater from tiles, sloped, or flat roofs:

• Use properly sized gutters or pipelines to collect the water.
• Filter and disinfect before storage.
• Store in a collection tank or storage structure.
• Place the storage tank above ground or underground.

Guidelines for Land-based Rainwater Harvesting

Land-based rainwater harvesting collects surface runoff from ground surfaces like fields and slopes into ponds, tanks, sand dams, and reservoirs to recharge the groundwater or for domestic, agricultural, or livestock use.

To collect rainwater through land-based methods, you must use the appropriate groundwater recharge structures or pits depending on the nature of the subsoil conditions. We highly recommend contracting a qualified engineer for these works.

You MUST own the land (have a valid title deed) or have a valid lease agreement to directly capture and store precipitation on a parcel of land in Kenya.

Rainwater Harvesting Guidelines for Agricultural Establishments

Rainwater harvesting is essential for agricultural establishments to support irrigation.  To comply with the water harvesting and storage regulations:

• Harvest and store rainwater sufficient for at least three (3) months' water demand.
• Submit a plan of water harvesting and applicable storage strategies to the Water Resources Authority if you’re harvesting water for commercial irrigation.

Take note that the Water Resources Authority or its agent may inspect your premises to ensure you’ve complied with the implementation report.

County Laws Supporting the National Regulations

Certain counties have also developed laws on rainwater harvesting, supporting the national regulations.

Kajiado County Rainwater Harvesting Act, 2020, for example, directs all private and commercial building owners to install rainwater harvesting and storage facilities. This harvesting infrastructure MUST be included in the building plan for approvals. The County government may contribute 50% of the installation costs to public institutions like schools and hospitals.

Vihiga County’s Water and Sanitation Services Act 2025 tasks the County Executive Committee (CEC) Member with developing and implementing a comprehensive Rainwater Harvesting and Storage Strategy. Under these regulations, the county government is expected to establish guidelines for roof catchments and storage systems across households, public institutions, and businesses.

How to Handle Storm Water Run-Off

Stormwater runoff is rain that flows over land, paved surfaces, and rooftops instead of soaking into the ground. Storm water can cause erosion, pollution, and flooding. Therefore, proper stormwater management is essential.

Stormwater management is a devolved function under the Constitution of Kenya (Fourth Schedule). Counties manage it via individual County Water and Sanitation Services Acts and Physical Planning Acts.

The water harvesting and storage regulations grant County Governments the authority to develop and enforce measures that ensure proper planning, management, maintenance, financing, expansion, and improvement of drainage systems and stormwater runoff collection within their jurisdictions. 

As we comply with the law, we also need to reconsider our designs. For example, a common feature of many development projects is compounds fully paved with cabros, leaving little to no grass or vegetation.

This creates a surface with low permeability that prevents water from soaking into the ground as fast as it should, resulting in heavy stormwater runoff and increasing the risk of urban flooding. This isn’t the only climate risk involved. In hot weather, you’ll experience increased local temperatures because the concrete retains and radiates solar energy, further contributing to human-induced climate change.

Not All Roof Types Can Safely Collect Rainwater

Some roofing types are unsafe for rainwater harvesting because they can leach toxic substances, degrade water quality, or trap contaminants.

Unsafe Roof Types for Rainwater Harvesting

• Asbestos roofs. They leach asbestos fibers, which are carcinogenic, into water. In March 2025, the Cabinet approved a nationwide asbestos removal initiative for all Kenyan public and private facilities. You need to contract a NEMA-licensed asbestos expert to handle, remove, and transport asbestos from your building. You also need an EIA license BEFORE removing asbestos.
• Old or peeling painted roofs. They may contain lead, chromium, and other heavy metals that may leach into the water.
• Bitumen/tar/felt roofing: These release hydrocarbons and organic compounds as they degrade under UV exposure from the sun. This changes the taste, smell, and colour of water, affecting its quality.

How an Environmental Impact Assessment (EIA) Applies to Rainwater Harvesting and Storage in Kenya

Rainwater harvesting is no longer simply a sustainability initiative. It’s increasingly becoming a legal and practical requirement for many developments in Kenya. By complying with the Water Act, the Water (Harvesting and Storage) Regulations, and applicable county laws, property owners can improve water security, reduce stormwater runoff, and contribute to climate resilience while avoiding potential compliance issues.

Depending on their scale and potential environmental impacts, projects such as sand dams, sub-surface dams, water pans, storage dams, and flood control works may require an Environmental Impact Assessment (EIA) licence under the Environmental (Impact Assessment and Audit) Regulations 2019. Seeking professional advice early can help ensure your project complies with all applicable environmental and water resource requirements.

Planning a project that may require environmental approvals or rainwater harvesting infrastructure? Our team can help you determine whether your development requires an EIA, prepare the necessary documentation, and guide you through the approval process. Contact us today for a free consultation.