Sander de Haas

SamSamWater launches the Rainwater Harvesting Tool. The Rainwater Harvesting Tool is a free online tool enabling everybody to easily calculate the optimal dimensions of a rain water harvesting tank for any location worldwide.



Visit http://www.samsamwater.com/rain or download the free app from the Google Play store (https://play.google.com/store/apps/details?id=com.b24.samsamwater).

Catching and storing rainwater from rooftops (‘roofwater harvesting’) is a proven technique which can provide a safe source of (drinking) water. Despite it being a commonly practiced method, many tanks (reservoirs) of roof water harvesting systems are over- or under-dimensioned, making the system unnecessary expensive or providing insufficient water. The rain water harvesting tool will help consumers, engineers and NGO’s to determine or check the optimum dimensions of a rainwater harvesting system.

In four easy steps you can calculate the optimum size of a rain water harvesting tank for your home, school or nursery. Based on your location, the available monthly rainfall is retrieved from a worldwide meteorological database. By entering the size of the roof (or drawing the roof on a map) and the type of roofing material the tool determines the amount of water that can be harvested. Finally, by entering the number of people using the system the water demand is calculated. Based on the monthly water availability and demand, the tool will determine the optimum tank size and will also give information on the expected reliability of the water supply system. The results are presented in a simple way so they can be used in for example project proposals or reports.

If you have questions, suggestions or if you would like more information on the SamSamWater Rainwater Harvesting Tool please contact us.

Today Sander de Haas gave a keynote presentation on ‘Low-cost innovations for water and sanitation’ at the InnoWater Symposium in Wageningen.

The presentation can be viewed below, and on this website: http://www.samsamwater.com/innowater.

Together with our partner organisation Kaalo Foundation we are involved in a proejct to construct improved berkads in Budunbuto, Somalia. Berkads are sub-surface water reservoirs to store water during rains so it can be used during droughts.

In the Somalia the construction of the berkads has started. The Kaalo Foundation has made a movie (in Dutch) about the construction:


More information on berkads can be found here.

Using the SamSamWater Climate Tool it is possible to determine climatic conditions (precipication and evaporation) for any location on earth. Last year the tool has been used over 58,000 times worldwide.

The climate data were extracted from a UN FAO server. Due to a server error, the tool has been dysfunctional for a number of months. But we are glad to announce the tool is fully functional again!

We use a different source for the climatic data (CRU CL 2.0), that’s why there might be a (limited) difference in the results compared to the old tool.

The use of the tool is very straightforward: select a location on the map, click ‘OK and you will see a chart and table with the average monthly precipitation and evaporation for that location.

SamSamWater Climate Tool

The Charity Fund of ING employees support SamSamWater with a donation of 1000 euros!

SamSamWater volunteer Dominique Woltheus works at ING and has supported this request.

We are delighted with this donation and would like to thank all ING employees!

Sander de Haas gave an interesting presentation on improving the in Somalia traditional water supply system “berkeds” at the meeting of Stichting Kaalo, Wilde Ganzen and Stichting 2015. The presentation can be found online:



If you have any questions regarding the presentation or project, please contact me.

During the meeting Stichting 2015 has donated € 50,000.- for the construction of berkads in Budunduto (Puntland, Somalia). SamSamWater provides technical assistance for this project. We would like to thank Stichting 2015 for this donation!


(photo Harry Kruiper)

Vrijdag 27 januari wordt er ter ondersteuning van de Groningen voor Afrika actie een Africa Night georganiseerd in Veendam. De opbrengsten van de avond komen ten goede aan SamSamWater!

Dit Afrikaans spectakel vindt plaats op vrijdag 27 januari vanaf 22.00 uur bij Bar Nadia
Kerkstraat 4, 9641 AR Veendam

Vrijdag 27 januari, aanvang 22:00 uur
Entree bedraagt € 2,50
Catering wordt verzorgd door TINA Keuken
Organisatie door UMHA


Unfortunately, this entry is only available in dutch. If interested, please use the automatic translation buttons in the left corner of this webpage.

Zaterdag 28 januariwordt er een bijeenkomst gehouden over Berked’s en fundraising voor Budunbuto in Puntland Somalië.

Sander de Haas zal daar een presentatie geven over het pilotproject dat we in samenwerking met Kaalo en Wilde Ganzen willen gaan uitvoeren in Somalië.

Tijdens de presentatie zal een uitleg worden gegeven over de manier waarop we het water in de berkeds (ondergrondse opslagreservoirs voor water) willen zuiveren tot schoon drinkwater.

Voor meer informatie over de bijeenkomst kunt u contact opnemen met Abdisalam Ali . De bijeenkomst wordt gehouden in de Evenementenhal Hardenberg en begint om 13:00 uur.

In 2011 the SamSamWater website received over 66,000 unique visitors from 203 different countries! Altogether they have have viewed over 170,000 pages! We would like to thank all our www.samsamwater.com-visitors!

We received many e-mails with questions, requests for support and words of thanks. It’s great to see our work is appreciated!

We would like to wish everybody a happy and successful 2012!

Last Thursday the poster ‘Artificial Recharge of Runoff Rainwater to Improve Spring Water Catchment‘ that Harry Rolf was presenting at the 6th RWSN Forum was awarded the prize for ‘Best Poster’ by the organizing committee and the Ministry of Water en Environment of Uganda.

Congratulations Harry!