Table 2. WTP Amount and the Gap between the Market Price^a.

authors	service for which WTP was investigated	study site	elicitation method	study population and context	mean/median WTP (adjusted for inflation and converted into 2022 USD)	ratio of WTP to price or cost (%)
Jenkins et al.7	manual emptying using a Gulper pump	Tanzania, Dar Es Salaam	CV: single-bound dichotomous choice	property owner (88%) or head of the longest tenant household (12%) from unplanned low-income areas	USD 31/300L (median)	153% (median)
Ross and Pinfold49	manual emptying	Rwanda, Kigali	CV: bidding game	households in two unplanned settlements	USD 95 (median)	NA
Peletz et al.10	formal manual emptying (Gasia Poa)b	Kenya, Kisumu	CV: double-bound dichotomous choice + open-ended question	live-in landlords, homeowners and tenants in low-income areas	USD 31 (median)	25–43% (median)
					USD 35 (mean)
Peletz et al.10	formal manual emptying (Gasia Poa)b by subscription/rent premium payment	Kenya, Kisumu	same as above	same as above	ranging from 44% of households willing to pay USD 3 to 12% of willing to pay USD 7 per month	NA
Delaire et al.51	formal manual emptying using a long-handled bucketc	Kenya, Kisumu	CV: double-bound dichotomous choice + open-ended question	(i) homeowners or landlords living on the premises and without adequate sanitation for themselves or all of their tenants or (ii) tenants without access to adequate sanitation in low-income areas	USD 29 (median)	27% (median)
					USD 34 (mean)	32% (mean)
Delaire et al.51	formal manual emptying using a Gulper pumpc	Kenya, Nakuru	same as above	same as above	USD 44 (median)	31% (median)
					USD 49 (mean)	35% (mean)
Delaire et al.51	formal manual emptying using a diesel pumpc	Kenya, Malindi	same as above	same as above	USD 49 (median)	40% (median)
					USD 60 (mean)	49% (mean)
Delaire et al.51	formal manual emptying using a long-handled bucketc	Ghana, Kumasi	same as above	same as above	USD 39 (median)	31% (median)
					USD 54 (mean)	44% (mean)
Delaire et al.51	formal manual emptying using a long-handled bucketc	Bangladesh, Rangpur	same as above	same as above	USD 12 (median)	13% (median)
					USD 18 (mean)	20% (mean)
Ross and Pinfold49	mechanical emptying with treatment	Rwanda, Kigali	CV: bidding game	households in two unplanned settlements across six cells in Nyarugenge district	∼USD 109 (median)	fully covered (>100%)
World Bank50	vacuum truck	Cambodia, Siem Reap and Kratie	CV: open-ended question	households in rural provinces	USD 14–19	39–55%
Burt et al.44	vacuum truck	Rwanda, Kigali	real-money voucher trial	landlords and households in dense informal settlements	USD 88 (revealed WTP)	152% (95% CI: 120–208%, mean)
Peletz et al.10	vacuum truck by subscription/rent premium payment	Kenya, Kisumu	CV: double-bound dichotomous choice + open-ended question	live-in landlords, homeowners and tenants in low-income areas	ranged from 52% of households willing to pay USD 2 to 6% willing to pay USD 5 per month	33–50% (median)
Peletz et al.10	vacuum truck	Kenya, Kisumu	same as above	same as above	USD 21 (median)	33–50% (median)
					USD 22 (mean)
Peletz et al.10	vacuum truck	Kenya, Kisumu	real-money voucher trial	same as above	USD 15 (mean, revealed WTP)	27–40% (mean)
Delaire et al.51	vacuum truck	Kenya, Kisumu	CV: double-bound dichotomous choice + open-ended question	(i) homeowners or landlords living on the premises and without adequate sanitation for themselves or all of their tenants or (ii) tenants without access to adequate sanitation in low-income areas	USD 20 (median)	34% (median)
					USD 21 (mean)	36% (mean)
Delaire et al.51	vacuum truck	Kenya, Nakuru	same as above	same as above	USD 29(median)	33% (median)
					USD 32 (mean)	36% (mean)
Delaire et al.51	vacuum truck	Kenya, Malindi	same as above	same as above	USD 25 (median)	18% (median)
					USD 33 (mean)	21% (mean)
Delaire et al.51	vacuum truck	Ghana, Kumasi	same as above	same as above	USD 39 (median)	42% (median)
					USD 38 (mean)	40% (mean)
Delaire et al.51	vacuum truck	Bangladesh, Rangpur	same as above	same as above	USD 18 (median)	20% (median)
					USD 14 (mean)	24% (mean)
Russel et al.45	CBS (twice-weekly collection)	Haiti, Cap Haitien	CV: single-bound dichotomous choice	households in an informal and formal settlement	USD 4.5/month (mean)	16%
Delaire et al.51	CBS (every few days collection)	Kenya, Kisumu	CV: double-bound dichotomous choice + open-ended question	(i) homeowners or landlords living on the premises and without adequate sanitation for themselves or all of their tenants or (ii) tenants without access to adequate sanitation in low-income areas	USD 2.0 (median)	22% (median, mean)
					USD 2.0 (mean)
Delaire et al.51	CBS (every few days collection)	Kenya, Nakuru	same as above	same as above	USD 2.0 (median)	23% (median)
					USD 2.4 (mean)	27% (mean)
Delaire et al.51	CBS (every few days collection)	Ghana, Kumasi	same as above	same as above	USD 3.9 (median)	55% (median)
					USD 4.6 (mean)	66% (mean)
Harder et al.46	septic tank emptying by water bill payment	Philippines, Dagupan	CV: single-bound dichotomous choice	households	USD 1.8/month	128%d
Parikh et al.42	improved pit emptyinge	Sierra Leone, Freetown	CV: open-ended question	households in urban area where over 90% of households use on-site sanitation facilities	USD 80 (mean)	116%
Balasubramanya et al.11	pit emptying that transports sludge away	Bangladesh, Bhaluka	CV: double-bound dichotomous choice	male heads of the pit-latrine owner household in Bhaluka, where sludge management services are being piloted by the government	∼USD 7.2	47%
Vásquez and Alicea-Planas47	excreta disposal by water bill payment	Nicaragua, Ciudad Sandino	DCE	households in an urban settlement with high population density and no emptying service	USD 3.9/month	NA
Naing et al.43	WTP for additional fee to request vacuum truck emptying through a phone call	Myanmar, Mandalay	CV: open-ended question	households in the five urban townships	USD 7–14 (median)f	NA
Harper et al.41	pit emptying that prevents contact with fecal sludge	Cambodia	DCE	households in rural provinces that owned a pour-flush latrine for more than 2 years and were present in a sales database	USD 69	NA
Harper et al.41	pit emptying that produces fertilizer from fecal sludge	Cambodia	DCE	same as above	USD 29	NA
Harper et al.41	pit emptying that reduces foul odor from high to moderate	Cambodia	DCE	same as above	USD 16	NA
Harper et al.41	pit emptying that reduces foul odor from moderate to none	Cambodia	DCE	same as above	USD 23	NA
Singh et al.48	emptying services by monthly payment	Bangladesh, Khulna	CV: open-ended question	households in a ward that represents a mix of planned and unplanned development, slum areas, and community of manual sweepers	77% said USD 0.9–4.5/month	107–535%g

^aMean or median WTP amounts are stated as WTP, unless otherwise noted as revealed WTP.

^bA trained service that worked with recognition of the local government and National Environment Management Authority (NEMA), had permission to dump waste at the city’s treatment plant, and complied with public health regulations.

^cA service delivered by trained, licensed, and vaccinated workers wearing protective gear. The workers minimize going inside the pits. They collect the fecal sludge into barrels and transport them to a treatment plant with pick-up trucks.

^dCalculated by authors based on the most probable scenario (3 year desludging interval).

^eA service that is easy to contact with emptiers, is timely and fast, leaves less dirt, and takes sludge away and safely disposes of sludge.

^fDue to a lack of data on the inflation rate and currency exchange rate, the original WTP amount (in 2017) is shown here.

^gCalculated by authors based on the most probable scenario (3 year desludging interval and 1.96 m³ average pit volume).