Design, performance, and demand for a novel in-line chlorine doser to increase safe water access

Abstract

Financially sustainable strategies are needed to increase access to safe drinking water in low-income settings. We designed a novel in-line chlorine doser that employs the Venturi principle to automatically add liquid chlorine at the point of water collection (tap outflows). The Venturi does not require electricity or moving parts, and users do not have to change the way they typically collect water. We field-tested the Venturi and assessed its technical performance and sales viability at water kiosks in Kisumu County, Kenya. We offered kiosk owners 6-month service packages to lease or lease-to-own the device; 27% of kiosks given a sales pitch committed to a service package. All but one kiosk paid in full during the 6-month service period and more than two-thirds purchased the device with payments totaling >$250 USD per kiosk. Kiosk customers could choose to purchase chlorinated or unchlorinated water from separate taps; 66% reported buying chlorinated water. Kiosk taps fitted with the Venturi had detectable free chlorine residual 97.6% of the time. The technical performance of the Venturi and effective demand from kiosks indicate high potential for the Venturi to increase safe water access in low-income communities.

Passive In-Line Chlorination for Drinking Water Disinfection: A Critical Review

“…Although WHO guidelines for residual in piped water systems recommend 0.2–0.5 mg/L FCR as adequate for disinfection, 49 some studies defined adequate chlorine delivery as any amount of measurable free chlorine above the limit of detection 17 , 32 , 38 , 40 , 44 , 45 or used their own range of desired doses on the basis of other standards. 21 , 33 , 34 , 42 , 46 , 48 Dosing consistency was reported as the percentage of samples with chlorine concentrations within the study’s indicated range ( Table 2 ).…”

“… 32 , 33 , 48 Stanford-MSR Venturi relies on the Venturi effect to pull chlorine into running water flowing through the chlorinator. 48 Zimba is a batch doser that relies on water reaching a specified level to trigger the addition of a fixed amount of chlorine. 33 Nirapad Pani, which was designed for use with handpumps (but not commercialized), uses suction generated by operating the handpump to pull liquid chlorine into the water.…”

“…Liquid chlorinators may have an advantage, as some studies indicate that liquid chlorine is easier to find and purchase in resource-constrained settings and can be more easily produced locally. 21 , 48 …”

“…was unavailable for a majority of the devices in Table 1 . Only four studies included in this review explicitly discussed financial viability, and only Powers et al 48 and Smith et al 40 evaluated implementation models for sustained financing and willingness and ability to pay for services. Two well-established methodologies in economics to evaluate individual or institutional ability and willingness to pay include take-it-or-leave-it (TIOLI) offers or BDM auctions.…”

“…Evidence for compatibility with an intermittent supply exists for a subset of the passive chlorinators reviewed here. 17 , 33 , 38 , 48 Other passive chlorinators presented in Table 1 require further development or evaluation of system requirements to maintain ideal dosing, particularly in intermittent and pressurized systems.…”