Exploring Types and Coverage of Sanitation: From Urban Sewers to Rural Latrines

Sanitation is one of those things most people take for granted – until it’s absent. For billions around the world, access to a safe, hygienic toilet remains a daily challenge. Sanitation isn’t just about toilets, though. It encompasses the entire system of managing human waste – from the moment it leaves the body to its final treatment and disposal. The technologies and approaches vary dramatically between well-serviced urban centres and remote rural villages, and the gaps in coverage, particularly in developing nations like India, reveal deep inequalities that directly affect public health.

How the concept of sanitation has evolved 🔗

For much of modern history, sanitation was narrowly defined as the safe disposal of human excreta. The focus was simple: keep waste away from human contact to prevent the spread of disease. Over time, however, this understanding has broadened considerably. Today, sanitation encompasses a much wider scope – including wastewater management, solid waste disposal, drainage systems, and hygiene promotion. The goal is no longer just to dispose of waste but to control the entire living environment to prevent disease and promote well-being.

This evolution is reflected in global policy frameworks. The WHO/UNICEF Joint Monitoring Programme (JMP) now tracks sanitation through detailed service ladders that go well beyond simple access metrics. The Sustainable Development Goal 6.2 calls for universal access to adequate and equitable sanitation and hygiene for all by 2030, including an end to open defecation – a target that is currently off track globally.

Urban sanitation technologies 🔗

In urban settings, the standard approach to sanitation revolves around a networked infrastructure: sewers collect wastewater, transport it to treatment plants, and the treated effluent is either discharged into water bodies or reused. This system, often called the water-carriage system, forms the backbone of urban sanitation in most developed cities.

Combined vs. sanitary sewers 🔗

Urban sewer systems generally come in two types. Combined sewers carry both domestic wastewater and stormwater (rainwater runoff) in a single pipe. Sanitary sewers, on the other hand, are dedicated exclusively to domestic and commercial wastewater, with stormwater handled separately through storm drains. In Indian cities, combined sewers are typically found in older, central urban areas, while newer developments may use separated systems.

Combined sewers have a significant drawback: during heavy rainfall, the system can overflow, releasing untreated sewage directly into rivers and water bodies. This is a well-documented problem in cities across the world, and it is especially concerning in India’s monsoon-prone regions.

Sewage treatment: primary and secondary processes 🔗

Once wastewater reaches a treatment plant, it goes through a staged process. Primary treatment is largely mechanical – it involves screening to remove large debris, grit removal to take out sand and gravel, and sedimentation to let heavier solids settle to the bottom. This stage removes a significant portion of suspended solids but leaves dissolved pollutants and pathogens largely untouched.

Secondary treatment adds a biological dimension. Methods like trickling filters (where wastewater flows over a bed of stones or plastic media coated with microorganisms) and the activated sludge process (where microorganisms break down organic matter in aerated tanks) are commonly used. These processes dramatically reduce the organic load and harmful pathogens in the effluent.

The infrastructure gap in Indian cities 🔗

Despite these well-understood technologies, India’s urban sanitation infrastructure is severely strained. According to a 2024 report in the Bulletin of the World Health Organization, only about 400 of India’s roughly 4,700 cities have sewerage networks. Urban India generates approximately 72,368 million litres of sewage per day, but installed treatment capacity covers only a fraction of that. According to the Stanford Social Innovation Review, a significant majority of India’s sewage reaches ponds, lakes, and rivers untreated, with centralized treatment systems in larger cities often failing due to high operational costs, power requirements, and maintenance challenges.

This leaves most urban areas dependent on on-site sanitation systems like septic tanks. While these can work well when properly installed and maintained, many septic tanks in Indian cities do not meet the required standards and function essentially as unmanaged sewage containers.

Rural sanitation facilities 🔗

The sanitation situation in rural areas presents a starkly different picture. Sewer networks are virtually non-existent in rural India. Wastewater typically drains into fields, open spaces, or eventually finds its way into canals and rivers. Where toilets exist, they are almost always individual household facilities rather than part of any networked system.

Types of rural sanitation facilities 🔗

Rural sanitation technologies fall into two broad categories:

Service-type (conservancy) systems rely on manual or mechanical removal of waste from latrines – a practice still found in some areas, though it raises serious health and dignity concerns, particularly when it involves manual scavenging.

Non-service-type (sanitary latrines) are self-contained facilities that do not require external waste removal services. These include:

Bore hole latrines – simple deep holes drilled into the ground, suitable for areas with low water tables. Pit latrines – the most basic form, consisting of a hole in the ground covered by a slab or platform. Water-seal latrines – feature a water trap that prevents odours and insects from rising back through the toilet. Septic tanks – underground chambers that provide partial treatment through sedimentation and anaerobic digestion. Aqua privies – a variation of the septic tank where the toilet seat is directly above the tank, with waste dropping into water below.

India’s rural sanitation challenge 🔗

Historically, rural sanitation coverage in India was extremely low. The 2011 Census revealed that only about 34% of rural households had toilet access. According to IFPRI, when the Swachh Bharat Mission launched in 2014, national rates of open defecation stood at roughly 60%, with the programme constructing 100 million toilets by 2020 and halving the open defecation rate within five years.

However, building toilets has not automatically solved the problem. Research published in PMC notes that despite government claims of 100% coverage, a significant share of the rural population continued to practise open defecation due to factors like lack of water supply, poor construction quality, cultural habits, and non-functional facilities. The gap between toilet construction and actual toilet use remains a persistent challenge.

The sanitation ladder: a global measurement tool 🔗

To make sense of the vast spectrum of sanitation practices around the world, the WHO/UNICEF Joint Monitoring Programme developed the concept of a sanitation service ladder. This framework classifies sanitation practices into ascending levels of service quality, helping policymakers track progress and identify gaps.

The rungs of the ladder 🔗

Open defecation sits at the bottom of the ladder. This means defecating in fields, forests, bushes, water bodies, or other open spaces. It is the riskiest sanitary practice, directly contaminating the environment and exposing entire communities to disease. UNICEF data from 2024 indicates that approximately 354 million people worldwide still practise open defecation.

Unimproved sanitation involves using facilities that do not adequately separate human excreta from human contact – such as pit latrines without slabs or platforms, hanging latrines, or bucket latrines.

Limited (shared) sanitation refers to improved-type facilities that are shared between two or more households. While the technology may be adequate, the shared nature of these facilities was historically considered a barrier to consistent hygiene.

Basic sanitation means using an improved facility that is not shared with other households. Improved facilities include flush or pour-flush toilets connected to sewers, septic tanks, or pit latrines; pit latrines with slabs (including ventilated improved pit latrines); and composting toilets.

Safely managed sanitation sits at the top of the ladder. This requires not just an improved, non-shared facility, but also that excreta are safely disposed of on-site or transported and treated off-site. This is the benchmark under SDG target 6.2.

Globally, progress has been steady but insufficient. According to UNICEF, between 2015 and 2024, 1.2 billion people gained access to safely managed sanitation services, raising global coverage from 48% to 58%. Yet 3.4 billion people – about two in five – still lack safely managed sanitation.

Sanitation coverage in India: progress and persistent gaps 🔗

India’s sanitation story is one of dramatic progress alongside enduring challenges. The Swachh Bharat Mission, launched in 2014, is widely regarded as the world’s largest sanitation programme. It catalysed a massive infrastructure push, with over 100 million toilets built and all states declaring themselves open defecation free by October 2019.

The numbers behind the transformation 🔗

According to WHO/UNICEF JMP 2025 data, India’s national open defecation rate declined to about 7% in 2024, with urban areas reporting near-zero open defecation and rural areas at roughly 11%. This is a remarkable shift from the situation in 2014, when rural sanitation coverage was reported at about 39%.

Yet the urban-rural divide persists. Urban sanitation coverage is significantly higher than rural coverage, but urban infrastructure faces its own crisis. Millions of people in urban slums lack adequate water and sanitation services. A large share of urban households connect only to open drains rather than closed sewer networks, and many have no access to drainage at all.

Beyond toilets: the wastewater challenge 🔗

Building toilets was the most visible part of the sanitation push, but the bigger, harder problem lies in managing what happens after the flush. India’s urban wastewater treatment capacity covers only a fraction of the sewage generated daily. Reporting by IndiaSpend highlights that over 72% of urban wastewater was being released untreated as of recent assessments, with many existing treatment plants underperforming due to poor maintenance and operational issues.

Phase 2 of the Swachh Bharat Mission (2020-2025) and the AMRUT programme have shifted attention toward solid and liquid waste management, faecal sludge treatment, and the sustainability of toilets that were built during Phase 1. The goal is to move India not just to an open-defecation-free status but towards ODF Plus – where communities also manage waste effectively.

Marginalised communities bear the greatest burden 🔗

Sanitation gaps disproportionately affect the urban poor, slum dwellers, and other marginalised communities. These populations often live in areas without sewer connections, alongside open drains and polluted water bodies. Women and girls are particularly affected, as inadequate sanitation compromises safety, dignity, and health. Addressing these inequities is essential for truly universal sanitation coverage.

The road ahead: from coverage to quality 🔗

India’s sanitation journey illustrates a critical global lesson: building infrastructure is only the first step. True sanitation progress requires sustained behaviour change, proper maintenance of facilities, effective waste treatment, and equitable access for all communities. The JMP sanitation ladder provides a useful framework, but climbing from basic to safely managed sanitation demands sustained investment, regulation, and community engagement.

Decentralised treatment systems, faecal sludge management plants, and nature-based solutions are emerging as practical alternatives to expensive centralised sewerage, particularly for smaller towns and peri-urban areas. The challenge now is to scale these solutions while ensuring that the toilets already built continue to be used and maintained.

What do you think? Can programmes like the Swachh Bharat Mission truly transform sanitation behaviour over the long term, or does lasting change require a fundamentally different approach? How can cities balance the need for large-scale sewer networks with affordable, decentralised alternatives?

References

1. https://washdata.org/topics/sanitation
2. https://www.who.int/news/item/05-07-2024-who–unicef-and-wateraid-host-global-sanitation-summit
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC11276156/
4. https://ssir.org/articles/entry/fixing_indias_sewage_problem
5. https://www.ifpri.org/blog/comprehensive-sanitation-in-india-despite-progress-an-unfinished-agenda/
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC8552289/
7. https://data.unicef.org/topic/water-and-sanitation/sanitation/
8. https://en.wikipedia.org/wiki/Swachh_Bharat_Mission
9. https://www.indiaspend.com/pollution/why-india-needs-to-urgently-rehaul-sewage-treatment-plans-954097