Beyond ‘improved’ towards ‘safe and sustainable’ urban sanitation: assessing the design, management and functionality of sanitation in poor communities of Dar es Salaam, Tanzania

This study assessed sanitation access in rapidly expanding informal settlements in Dar es Salaam (Dar) against eight proposed indicators of hygienic safety, sustainability and functionality, and in relation to the Millennium Development Goal (MDG) ‘improved’ sanitation definition. Information was collected on toilet facility designs, management and functionality through a structured interview and observations at 662 randomly selected residential properties across 35 unplanned, low-income subwards of Dar. Trends in access and associations with sharing, occupancy, latrine replacement, income, education and location factors were considered through statistical analyses. Surveyed subwards were open-defecation free. While 56% of households used a facility that met the MDG improved technology definition, only 8% had a functional facility that could be considered as hygienically safe and sustainable sanitation. Safe, sustainable, functioning sanitation access was 2.6 times greater among the richest quintile than the two poorest quintiles. Very poor sanitation services among Dar’s urban poor arise from widespread lack of access to hygienically safe pit emptying services, unhygienic designs and functionality problems (affecting 67, 55 and 29%, respectively). As new goals and targets beyond 2015 are discussed, these findings may have important implications for defining what constitutes ‘improved’ sanitation for poor populations living in unplanned informal


INTRODUCTION
Sanitation is an important foundation for health, economic development and well-being (Bartram & Cairncross ; WSP ). In developing countries, urban areas are estimated to have higher sanitation coverage than rural areas (WHO/UNICEF a) but these statistics often mask the severity and complexity of sanitation challenges affecting towns and cities and the urban poor in particular. Sanitation realities in slums and informal settlements where the urban poor live are inevitably diluted in representative national results of official monitoring surveys or may be under-represented or completely missed, for example when they constitute small pockets within enumeration areas, are poorly defined, or enumerators are frightened to visit them (Fry et al. ; Hancioglu & Arnold ).
A further limitation is that access within a city is rarely disaggregated spatially and economically (Fry et al. ; UNICEF ).
The current generalized approach of defining sanitation access as single household use of an 'improved' toilet technology (WHO/UNICEF ) may be less appropriate for rapidly growing cities where on-site sanitation technologies such as pit latrines, pour flush latrines and septic tanks continue to be used despite ever-increasing urban densities. In such situations, sanitation facilities are likely to be emptied rather than moved (Thye et al. ) so that the safety of sanitation systems depends at least as much on provisions for safe fecal sludge management including emptying, removal, treatment and disposal or reuse, as on safe fecal capture and containment (i.e. the design of the facility) (Barrenberg & Stenström ). Evaluating whether on-site sanitation facilities are functional, a measure of users' ability to maintain them, is also crucial for assessing access.

METHODS
An extensive survey undertaken in Dar in June 2008 (the start of the dry season) of household sanitation facilities and associated practices, costs, preferences, perceptions and plans forms the basis for this study. The survey was designed to gather consumer insights and a baseline to develop demand-responsive sanitation upgrading strategies for Dar's urban poor.

Sampling design
Thirty-five unplanned, low-income, high-density sub-wards (average 379 persons/hectare) were identified by Dar's three municipal councils (MC) for upgrading, representing approximately 20% of the unplanned population. Residential properties were chosen as the sampling and analysis unit, since on-plot sanitation facilities are organized and managed at property level. Population proportional sampling, following a two-stage process, was used to select a representative random sample of 662 residential properties across the 35 sub-wards (2% of all properties). Each sub-ward (i) was assigned its share (S i ) of the sample, according to its 2002 population. Starting at a random

Household survey
The survey consisted of a structured questionnaire administered verbally to the property owner or the oldest tenant in the absence of the owner, supplemented by structured spot observations of the toilet facility and plot. Following exploratory focus group discussions with owners and tenants, the survey was designed to characterize sanitation facilities (below and above ground design), age and condition; to document latrine use, operating and maintenance practices; and to collect past and anticipated expenditures and plans for construction, replacement, improvement and pit emptying. The survey also assessed facility design and emptying preferences and perceptions of sanitation conditions and problems. At each property, GPS coordinates and respondent socio-economic characteristics were collected. Trained professional surveyors from Research International conducted the survey. This study draws on a sub-set of the survey data related to facility design, management and functionality to assess the safety and sustainability of on-site sanitation systems in study settlements.

Structured observations
'Flooding out', also known as 'vomiting' is a method of partial emptying of pits which involves inserting a drain or opening into an exposed or elevated portion of the latrine pit wall, below the slab in order to release fecal sludge into the open environment to be washed away by storm water during rains. In some cases, rising water tables during rain events and excess flooding may increase pit sludge levels to the level of the opening, where it is divulged or 'vomited' out. In light of growing concerns over this unsanitary pit-emptying practice, surveyors were trained to look for and record the presence of a 'flooding out' pit waste drain pipe during structured spot observation of each facility. They also observed the functional state of facilities in terms of slab structural condition, fullness of the waste pit/ tank and status of the superstructure. Pit fullness was judged by observing the height of void space between the slab or cover and the surface of the sludge. To understand barriers to safe pit emptying, surveyors observed physical accessibility of the property to a small car or tanker vehicle. Table 1 describes eight indicators developed to assess the safety and sustainability of on-site sanitation systems in study communities. The first three (1-3) assess the technical design of the facility, the next two (4 and 5) assess availability and access to safe fecal waste management services, and the last three (6-8) assess the functionality of the facility at the time of the survey.

Indicators of improved and safe and sustainable sanitation
Inclusion of pit lining as a safe and sustainable design indicator (#3) accounts for two considerations. First, lining is structurally necessary to prevent pit collapse in areas with flooding, poor drainage or high water tables, conditions widely present in poor neighborhoods of Dar (see Table A1 in the Supplemental Material available online at http://www. iwaponline.com/washdev/004/180.pdf) and frequent characteristics of undesirable lands where the urban poor reside.
Second, lining also facilitates emptying of full pits while unlined pits, for the most part, cannot be emptied using hygienic mechanized suction methods and risk damage or collapse even when manual means are used (Koné & Strauss ).

Sample description
A majority of properties (51%) were family-owned and occupied, with the balance consisting of landlord-tenant (39%) and tenant-only (absentee landlord) (10%) properties. On average, 3.5 households and 10 people, including 2.2 children 3 years, resided at each property.

Above and below ground design
The above (AG) and below (BG) ground design of each facility (Table 2) and slab material were used to assess facilities in terms of improved and safe and sustainable fecal capture. Simple slab over pit designs ('traditional pit latrine') were the most common AG design. About 36% of facilities had unlined pits. Most facilities were operated as wet systems owing to anal cleansing with water and no separate bathing place, posing increased fecal

Facility construction expenditures
Expenditures for on-plot sanitation facilities, including initial construction and subsequent improvement, were evaluated for facilities built in the 10 years preceding the survey (see Table A2, which is available online in the Supplemental

Facility condition
Over 40% of facilities were full or nearly full (<25 cm of full); only 5% were >1 m empty. One in five had a badly cracked or collapsing slab, or was in a state that prohibited safe use. Three-quarters lacked a roof, 19% lacked a door and 6% lacked walls. Owners of facilities in poor structural condition or with inadequate superstructures had significantly lower incomes compared with others. No income difference was found between owners with and without completely full pits, suggesting factors beyond ability to pay account for the high rate of full pits.

Interrupted use
More than one in six toilet facilities had been unusable at some point in the past because it had collapsed, the pit was full or improvements were being made (see Table A3 including slab repair (a common additional expense incurred), was $57. It varied by method, but differences were not significant.

Access to safe and sustainable facilities
Sanitation facility designs were assessed against indicators 1-3 (Table 1) to estimate safe and sustainable facility access rates (Table 3). While 59% of facilities met the JMP improved technology definition, fewer (41%) met our hygienically safe and sustainable criteria. In population terms, 45% had access to a safe and sustainable sanitation facility.
Pit waste drain pipes (28% prevalence) associated with flooding out were a significant cause of failure to meet both improved and safe and sustainable design criteria, while use of unlined pits further reduced safe and sustainable facility access.

Access to safe emptying services
More than half of properties reported local availability of at least one of the hygienic emptying services; however, physical plot access by a small car or tanker vehicle was low (Table 3). Consequently, only 33% of the population in study areas had access to safe emptying services.

Access to safe and sustainable sanitation systems
Properties with both a safe and sustainable sanitation facility and access to a safe emptying service (hence, to a safe and sustainable sanitation system), made up just over 13% of properties and served 14% of the study population (  compared with family-owned/occupied residences (30%).
Sharing was positively associated with safe and sustainable facility access and with facility functionality (see Table A4, which is available online in the Supplemental Material at http://www.iwaponline.com/washdev/004/180.pdf). Those sharing their facility were about 40% more likely to have a functional, safe and sustainable sanitation system than those using non-shared facilities (p ¼ 0.17). We hypothesize economic factors may explain some of these observations: greater cash resources from multiple poor households are available for building, maintaining and operating a shared facility than from a single poor household for their own facility, and landlords in poor, unplanned areas of Dar are able to obtain higher rents when they offer better quality sanitation facilities to their tenants. The latter hypothesis is borne out by our data on reported rents among the small subset of tenant respondents (n ¼ 79), showing an average premium of TSH4,500 to 6,100 more in rent per month paid by tenants with access to an improved sanitation facility and to a safe, sustainable and functional facility, respectively. Neither improved nor safe pit-emptying access was associated with sharing.
A positive association between sharing and safe and sustainable system access runs counter to the JMP assumption that facility sharing diminishes public health safety and renders sanitation 'unimproved'. While shared facilities were used on average by significantly more users (11) than single household facilities (8.4), the difference was relatively small (2.6 people). Shared facilities were nearly all private, on-plot residential facilities (99%) shared among extended family members (25% of sharing) or among non-related households residing at the same property (75% of sharing).
Tenant-only houses were significantly more likely to have access to an improved facility compared with mixed landlord-tenant and family-only houses, but their facilities were significantly less likely to be functional (Table A4). Tenantonly houses also had greater access to safe and sustainable facilities and safe emptying services than family-only properties, but these differences were not significant. Tenant-only properties in Dar do not appear to be disadvantaged in terms of the hygienic and sustainable standard of facilities or safe emptying service access, but rather encounter challenges with maintenance resulting in lower functionality.

Replacement facility and residency plan access
Replacement latrines were more likely to have safe and sustainable designs (p ¼ 0.18) than original latrines, and were significantly more likely to have safe emptying service access (p < 0.001), resulting in a nearly 50% greater rate of safe and sustainable sanitation system access for replacement over original latrines (p ¼ 0.06). However, replacement latrines were somewhat less likely to be functional mainly because they were more likely to be full than original latrines. Households may be motivated to replace and upgrade their facilities with safe and sustainable designs when safe emptying services are plot-accessible and locally available to empty them.
Residency plans were associated with access in several ways (Table A4). Those uncertain about plans (36%) were least likely to have access to an improved or safe and sustainable facility but had better access to safe emptying services, compared with properties where the respondent had longterm plans; these differences were significant. Landlords uncertain about their residency plans may prefer not to invest in better sanitation facilities at the property, while uncertain renters may prefer not to pay the rental premium for better sanitation facilities.

Household income and education effects on access
Nearly all components of safe, sustainable and functional access showed significant income effects (Table A4)

This study examined sanitation access and equity in Dar es
Salaam looking beyond the current MDG definition of Applying these new, more rigorous indicators, we found access to adequate sanitation facilities in Dar's unplanned areas to be far lower than current JMP estimates. We also found significant income-associated, educational and spatial disparities in adequate access across low-income, unplanned