Department Sanitation, Water and Solid Waste for Development

Estimating quantities and qualities (Q&Q)

Sustainable management of faecal sludge requires reasonable estimates of the quantities and qualities (Q&Q) that are accumulating at community to city-wide scale. In situ Q&Qs of faecal sludge are difficult to estimate, as faecal sludge is often stored underground in containments, records frequently do not exist, and construction is not standardized, but estimates are necessary for planning scenarios as it represents the total amount and characteristics of faecal sludge that needs to be managed. For more on measuring in situ volumes of faecal sludge, refer to the  Volaser. In the past, people have estimated Q&Qs based on literature values from other contexts, or educated guesses from users and emptying service providers, but these estimates were not adequate to capture the desired accuracy and range of variability.

To address this deficiency, a methodology was developed by Eawag/Sandec, using forms of demographic (e.g. income level, number of users), environmental (e.g. soil conditions, groundwater), and technical (e.g. containment type, inputs to containment) forms of data to group together accumulated Q&Qs of faecal sludge to make localized projections. Demographic, environmental, and technical (DET) forms of data are also spatially analyzable, which is important for city-wide planning. This methodology has evolved during implementations in seven cities, and is now fully described in a book chapter in the IWA publication ‘Methods of Faecal Sludge Analysis’, which can be found here. Further developments we are working on to improve the methodology include remote sensing, and different types of machine learning and predictive modeling

Publications are listed below, steps in methodology development include:

  • Q&Q studies in Kampala, Uganda, and Hanoi, Vietnam, where the first sampling plans were tested during conceptualization of the methodology.
  • Two Master theses in Dar es Salaam, Tanzania, which looked at Q&Q on a neighborhood scale. The first conceptualization tests for the Volaser were also done here.
  • Determining Q&Q of faecal sludge in Sircilla, a small town in India, where different methods for measuring faecal sludge accumulation rate were tested and compared.
  • Collaboration with the Systems Analysis & Modeling department at Eawag to analyze spatial patterns in Q&Q data, and to explore whether models could be made from existing data that can be used in the future for making predictions with increased accuracy at a lower cost.
  • Large scale Q&Q study in Lusaka, Zambia, where the objective was to make estimates of accumulating faecal sludge Q&Qs in Lusaka. 400+ samples were taken in situ from onsite sanitation technologies all over the city.
  • Sharing of raw data for 845 samples taken in four cities (180 Kampala, Uganda, 80 Hanoi, Vietnam, 164 Sircilla, India, 421 Lusaka, Zambia)


  • Makarere University
  • National Water and Sewerage Corporation (Uganda)
  • Hanoi University of Civil Engineering
  • University of Dar es Salaam
  • University of Zambia
  • CDD Society
  • Kwame Nkrumah University of Science and Technology
  • CubeX
  • 500B Solutions
  • GOAL Sierra Leone
  • Sanivation

Current funding

  • DEZA

Previous funding

  • GIZ
  • SECO


Andriessen, N.; Appiah-Effah, E.; Browne, S. J. I.; al Jahjah, R.; Kabika, J.; Kinobe, J. R.; Korir, N.; Nishimwe, P.; Niwagaba, C. B.; Pradeep, R.; Prasad, P.; Tembo, J. M.; William, A.; Ambuehl, B.; Strande, L. (2023) Quantities and qualities of fecal sludge: experiences from field implementation with a Volaser in 7 countries during a pandemic, Frontiers in Water, 5, 1130081 (14 pp.), doi:10.3389/frwa.2023.1130081, Institutional Repository
Strande, L.; Englund, M.; Andriessen, N.; Carbajal, J. P.; Scheidegger, A. (2021) Estimating quantities and qualities (Q&Q) of faecal sludge at community to city‐wide scales, In: Velkushanova, K.; Strande, L.; Ronteltap, M.; Koottatep, T.; Brdjanovic, D.; Buckley, C. (Eds.), Methods for faecal sludge analysis, 115-144, Institutional Repository
Englund, M.; Carbajal, J. P.; Ferré, A.; Bassan, M.; Hoai Vu, A. T.; Nguyen, V. A.; Strande, L. (2020) Modelling quantities and qualities (Q&Q) of faecal sludge in Hanoi, Vietnam and Kampala, Uganda for improved management solutions, Journal of Environmental Management, 261, 110202 (13 pp.), doi:10.1016/j.jenvman.2020.110202, Institutional Repository
Englund, M.; Carbajal, J. P.; Strande, L. (2018) Method to estimate quantities and qualities of faecal sludge, Sandec News, 19, 8-9, Institutional Repository
Strande, L.; Schoebitz, L.; Bischoff, F.; Ddiba, D.; Okello, F.; Englund, M.; Ward, B. J.; Niwagaba, C. B. (2018) Methods to reliably estimate faecal sludge quantities and qualities for the design of treatment technologies and management solutions, Journal of Environmental Management, 223, 898-907, doi:10.1016/j.jenvman.2018.06.100, Institutional Repository
Schoebitz, L.; Bischoff, F.; Lohri, C. R.; Niwagaba, C. B.; Siber, R.; Strande, L. (2017) GIS analysis and optimisation of faecal sludge logistics at city-wide scale in Kampala, Uganda, Sustainability, 9(2), 194 (16 pp.), doi:10.3390/su9020194, Institutional Repository
Schoebitz, L.; Bassan, M.; Ferré, A.; Vu, T. H. A.; Nguyen, V. A.; Strande, L. (2014) FAQ: faecal sludge quantification and characterization – field trial of methodology in Hanoi, Vietnam, In: WEDC conference 37, 1954 (6 pp.), Institutional Repository
Schoebitz, L.; Niwagaba, C.; Francis, O.; Bischoff, F.; Strande, L. (2014) FAQ: faecal sludge quantification and characterization – Kampala, Sandec News, 15, 12-13, Institutional Repository
Bassan, M.; Tchonda, T.; Yiougo, L.; Zoellig, H.; Mahamane, I.; Mbéguéré, M.; Strande, L. (2013) Characterization of faecal sludge during dry and rainy seasons in Ouagadougou, Burkina Faso, In: WEDC conference 36, 1814 (6 pp.), Institutional Repository
Prasad, P.; Andriessen, N.; Moorthy, A.; Das, A.; Coppens, K.; Pradeep, R.; Strande, L. (2021) Methods for estimating quantities and qualities (Q&Q) of faecal sludge: field evaluation in Sircilla, India, Journal of Water Sanitation and Hygiene for Development, 11(3), 494-504, doi:10.2166/washdev.2021.269, Institutional Repository


Development of SPA-DET Approach for Faecal Sludge Quantities & Qualities. Andriessen, N., Renggli, S., & Strande, L. Sandec News, 2020

Supplementary information: GIS analysis and optimization of faecal sludge logistics at city-wide scale in Kampala, Uganda. Schoebitz, L., Bischoff, F., Lohri, C.R., Niwagaba, C., Siber, R., Strande, L.  Eawag/Sandec April 2016

Results of faecal sludge analyses in Kampala, Uganda: Pictures, characteristics and qualitative observations for 76 samples. Schoebitz, L., Bischoff, F., Ddiba, D., Okello, F., Nakazibwe, R., Niwagaba, C.B., Lohri, C.R., Strande, L. 2016

Local Factors Influence FS Characteristics: Research in Hanoi, Vietnam. Bassan, M., Ferré, A., Nguyen, V.A., Holliger, C., Strande, L. Sandec News 2015


Nienke Andriessen Project Officer Tel. +41 58 765 5082 Send Mail