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• Nicaragua

Home Biofilters - Biological filters to remove greywater nutrients
Implementing home Biofilters in other countries

This technology is simple to implement and does not require skilled labour. The construction method follows the concept: self-built with technical assistance, so that the families who choose this alternative can themselves build the biofilter, with technical support. Based on experiences, the methodology when applied to other countries could include the following steps:

Involvement of competent institutions

The first step is to involve national institutions responsible for water and sanitation, and social organizations interested in participating in the implementation of biofilters. For example, in Nicaragua ISSUE-2’s main partners carry out the following functions:
• Centro de Investigación y Estudios en Medio Ambiente CIEMA: with their experience in the construction of biofilters in the country, they provide statistical data for the design of home biofilters, in accordance with the environmental, biological and indigenous conditions of the region. CIEMA evaluates the effectiveness of biofilters, comparing influent and effluent water.
• Delegación V Alcaldía de Managua: promotes home biofilters among inhabitants as an alternative form of greywater treatment to improve the environmental conditions of neighbourhoods that do not have sewage services.
• HABITAR: identifies families interested in using this technology, funded through micro-credits. HABITAR is responsible for training the local workforce and families, also providing technical assistance before and during the construction of the systems.
• Asociación de Microfinacieras de Nicaragua ASOMIF: manages a guarantee fund to channel micro credit to the environmental services sector and facilitates access to funds for low-income families interested in implementing home biofilters.

Promotion and awareness campaign

The main aim of the campaign is to show residents how they can raise their living standards through proper sanitation, and demonstrate the effectiveness of biofilter technology for the treatment and recovery of greywater, highlighting the benefits in both environmental and economic terms. At the same time, users are encouraged to provide proper maintenance to keep the system efficient

Location and site

A survey is carried out of the households that wish to acquire the technology and then an assessment is made of the area available for location. To define the site or area where the biofilter is installed it is important to:
• Analyse the locations of influent and effluent of greywater (bath, laundry, disposal site, etc).
• Verify that the site is level, taking into account that the land should not have a slope of more than 5 percent.


Economic sustainability for the acquisition of biofilters is promoted through social credit, which originates from donations. The maximum term is one year with an annual interest rate of 7%. Taking into account the economic situation of the people, repayments are agreed in consultation with users and are either fortnightly or monthly. Credit is given in the form of building materials, prior calculation and agreement with the participating families.

Home biofilter design

A study is made of the number of people per household, water usage, provision of drinking water, in order to estimate the equipment needed and possible daily discharge of water from the households. These data are necessary to design the biofilter to the right size.

Note that a standard model does not exist for this technology because each is designed with different conditions in mind; however, it is possible to set a standard when working in highly homogenous areas.

Technical assistance throughout the process

Workshops are organized for the families that are constructing a biofilter so that they are directly involved in the work. Technical assistance is given at different stages of homes biofilter implementation, starting with capacity building, then during construction and on completion of the system.

HABITAR has experience in transferring knowledge of the design and construction of this technology to technicians, who do not necessarily have to be specialists in the subject. As it is a simple system, theory and practice can be learnt workshops. So far in Nicaragua more than 90 technicians have been trained in different regions of the country and this has facilitated the promotion of the technology, which is now incorporated in the design of projects by trained technicians.