Prepared for Renaissance Philanthropy·Fund Ecosystem Program·July 2026

The Water for Health Fund

Cost-effective health impact, from the molecule to the market.

The fund's primary metric is the marginal donor cost per averted DALY. Third-party revenue pays for safe-water delivery so philanthropy does not have to; carbon credit revenue is the proven, contracted example. One bottleneck, the integrity and cost of verifying safe water, keeps that revenue from flowing. Clearing it is a field-level public good that only philanthropy will fund.

$30M$10M into the existing footprint immediately · $20M for new programs and models
Avery Bang, MBA
Chief Fund Manager · Deal Flow Manager
Senior Principal, Mulago Foundation
Evan Thomas, PhD, PE, MPH, MBA
Co-Fund Manager · Program Director
Mortenson Center, CU Boulder · Founder & CEO, Virridy
29%
reduction in under-five diarrhoea in a cluster-randomized trial (Rwanda)
2.79M
people reached today by 7 programs in 6 countries
1,273
continuously monitored water points
$25M
carbon offtake under contract with PetroChina, Louis Dreyfus, and Mortenson
$40M
blended structure: this $30M ask paired with $10M Bridges debt in advanced due diligence
01The Objective

Buy averted DALYs at a marginal donor cost that falls toward zero

Safe drinking water is among the interventions GiveWell rates most cost-effective in global health, concentrated on the highest-mortality group: children under five. The fund's job is to finance that impact so that each philanthropic dollar is a one-time input, not a recurring subsidy.

4B
people drink water contaminated with fecal matter (Greenwood et al. 2024, Science)
444,000
annual deaths of children under five from diarrhoeal disease (WHO 2024); ~297,000 attributable to inadequate WASH
$37.6B/yr
capital investment needed to meet the drinking-water SDG, roughly 3× current levels. Grants alone cannot close this.
Donor cost per averted DALY ↓
The mechanism: third-party revenue, carbon credits first among it, pays for delivery. Every dollar of outside revenue is a dollar of recurring donor funding no longer needed, so the marginal donor cost per averted DALY falls toward zero as revenue takes over.

Other third-party streams, results-based public finance and commercial water-quality revenue among them, follow the same logic. Carbon is where the contracts already exist.

02The Problem

A financing barrier rooted in measurement

A water credit requires evidence that treatment is used and that the delivered water is safe. Both measurements are broken, and the market prices that in.

Usage is self-reported, and overstated

In carbon-financed water filters in Kenya, reported use was 81%; measured use was approximately 19% (Pickering et al. 2017). Over-reporting of comparable WASH behaviors runs 50 to 60%. For cookstoves, the most analogous credit class, issued credits were over-credited by an average factor of 9.2 (Gill-Wiehl et al. 2024).

Water testing is sparse and expensive

Culture-based laboratory testing costs $12 to $15 per sample, needs cold-chain logistics and 24 to 48 hours to a result, and is typically run once or twice a year. It cannot confirm water is safe between tests, when failures and recontamination actually occur, and it cannot scale across a portfolio.

Theory of change: add monitoring and revenue, close the loop
Today: an open, linear flow. Capital is consumed.
Donors fund capex
one-time grants build water systems
→
No monitoring
water quality and health impact go unmeasured
→
No O&M revenue
little or nothing to operate and maintain with
→
Systems fail
donors rebuild from zero
no revenue returns: the loop never closes
✗ No revenue returns: the loop never closes, and donors rebuild from zero.

Without measurement there is no performance signal, and without revenue there is no operation and maintenance. Donor-funded systems fail and get rebuilt, and the donor cost per averted DALY never falls.

03Current Footprint

Monitored, verified water across Africa, and this expands

These are carbon-credit-generating drinking-water projects the team manages and verifies with the Lume today. Every project is continuously monitored at the water point, and that same data generates the credits. The first $10M tranche deploys into this footprint immediately.

1,273
monitored water sites
2.79M
people served
6
countries with active programs
Gold Standard
registered developer
  • Rwanda
    Amazi Meza, schools (flagship)
  • Kenya
    Millennium Water Alliance & LifeStraw
  • DR Congo
    Asili, water kiosks
  • Burundi
    Amazi Water
  • Tanzania
    Water Mission
  • Madagascar
    Helvetas
Today · $10M deploys here immediately
7 programs, 6 countries, 2.79M people, 1,273 continuously monitored water points, $25M in contracted offtake
→
The expansion · $20M for new programs & models
New implementers, geographies, and delivery models brought to creditable, financeable status; ~9M people served and ~7.6M credits at full portfolio scale, with the open standard reaching the wider class of the 1.2B people who boil drinking water

Registry and offtake partners: Gold Standard · PetroChina · Louis Dreyfus Company · Mortenson · Millennium Water Alliance. Across the group's 1,273 monitored sites, the live project map shows every site and region.

04The Monitoring & Verification Technology

Real hardware in real water

The Lume is a fielded instrument, not a concept: a reagent-free sensor, developed at the University of Colorado Boulder, that reads microbial contamination continuously using tryptophan-like fluorescence (TLF), where a standard laboratory culture takes 18 to 24 hours per sample. Because it measures the treated water rather than the device or the user's behavior, one verification standard serves every delivery modality.

A Lume sensor deployed in a mountain stream
A Lume deployed in-stream: solar or battery powered, cellular-connected, streaming microbial water-quality data in real time.
60 s
to a microbial reading, vs 24 to 48 hours for culture
<0.1 ppb
tryptophan detection limit in deionized water
216
paired sensor-versus-reference validation observations
TRL 7
patented (US 11,506,606; 11,507,861), field-deployed in Sub-Saharan Africa; ~$0 marginal cost per reading vs $12 to $15 per lab sample

The proof

85% balanced accuracy
on the drinking-water safe/unsafe decision vs Compartment Bag Tests (76% sensitivity, 93% specificity)
R² = 0.881 / 0.872
Colilert-trained vs Colilert (n=209) and MF-trained vs membrane filtration (n=303): stronger agreement than the two EPA-approved lab methods achieve with each other (R² = 0.572). The sensor is method-agnostic.
κ = 0.88 vs 0.40
"almost perfect" categorical agreement with Colilert, versus only "fair" agreement between the two lab methods themselves
96.8%
binary classification accuracy on the Seine River, Paris (3 TLF sensors); 100% on chlorinated Kenyan boreholes (n=30)
86%
of continuous-Lume predictions on Boulder Creek grabs (n=81) agree with Colilert within the lab's own 95% measurement uncertainty
Pilot 14
Gold Standard pilot-level methodology deviation for TLF digital monitoring (Sept 2025), the first for an IoT sensor; design and validation published in Water Research (Knopp et al. 2026)

Categorical classification vs Colilert

Three-level exceedance classifier (Low <126 / Mid 126–1,000 / High ≥1,000 CFU/100 mL) across all validation sites (n=90). Rows are the sensor's predicted class, columns the Colilert-measured class; green diagonal is correct. Overall accuracy 0.86, quadratic-weighted κ 0.70.

Why this matters for the credit

The Lume builds an auditable, timestamped, continuous record of water safety at the point of consumption, in place of a handful of annual laboratory snapshots. The fund's asset is not the sensor; it is the accepted, open verification standard the sensor makes possible. The same record that makes the credit creditable is the measured safe-water consumption that GiveWell's cost-per-DALY model most depends on.

The fund's asset is not the sensor. It is the accepted, open verification standard the sensor makes possible: an auditable, timestamped, continuous record of water safety at the point of consumption, in place of a handful of annual laboratory snapshots. The same record that makes the credit creditable is the measured safe-water consumption that GiveWell's cost-per-DALY model most depends on.

05What the Fund Does

Four catalytic functions, then exit

Not a single-instrument grant program for sensors: the set of public goods and de-risking capital that makes high-integrity, revenue-financed water treatment function as a market. Amounts shown are the $10M tranche-1 deployment into the existing footprint; the $20M second tranche extends the same functions to new programs and models.

$4.0M · CO-LEADING USE

De-risk the carbon projects

Catalytic first-loss capital that absorbs early losses on forward carbon revenue, plus the upfront project development the credit will not pay for in advance: baselining, monitoring build-out, registration. Blended-finance deals have historically mobilized ~$4 of commercial capital per $1 of concessional capital.

$3.5M · CO-LEADING USE

Lume development, validation, and acceptance

Hardening the sensor for field conditions across six countries and every modality, paired sensor-versus-laboratory validation at portfolio scale, and driving Pilot 14 to a full Gold Standard digital-MRV methodology. Project- and method-specific work, not Virridy's commercial product roadmap: the classic translation of university IP into an accepted, revenue-bearing standard.

$1.0M

Methodology and standards

Codify digital MRV with Gold Standard and other registries and strengthen the integrity of the safe-water credit class, a benefit that accrues to every implementer.

$1.0M

Implementer capacity and demand aggregation

Support water-treatment implementers in accessing carbon markets, and aggregate buyer demand for independently verified, high-integrity water credits. ($0.5M additionally funds fund operations and governance.)

The fund does not finance the water systems themselves; those are paid for by the revenue the fund unlocks. It does not finance any implementer's commercial operations.

06Fund Architecture

Two vehicles, no shared expenditures

The governing design principle: philanthropic capital never subsidizes a commercial venture. The integrity test is that no expenditure is ever charged to both vehicles.

Philanthropic · this ask
$30M

Water for Health Fund

  • $10M into the existing footprint immediately; $20M for new programs and models
  • Grants and, potentially, first-loss capital; no market return
  • Verification infrastructure, methodology, de-risking, capacity
  • Benefits the credit class and its implementers, sector-wide
  • Multiple implementers; the operator is one of several
Commercial · in advanced due diligence
$10M

Production entity, debt from the Bridges SDG Outcome Fund

  • Repayable debt and equity, return-seeking
  • Working capital to produce and deliver already-contracted credits
  • Benefits the production entity's balance sheet
  • At full scale: ~7.6M credits, ~$176M gross credit revenue through 2033
≈ $40Mblended structure. Commercial debt funds production of de-risked, contracted credits; it cannot take pre-commercial project risk or fund shared validation, because those return no cash and benefit the whole class. That layer is this fund.

Governance

Because the proposed co-fund manager and program director also leads Virridy, the largest single implementer, allocation is implementer-neutral by construction: fund management, capital allocation, and deal flow sit with the proposed chief fund manager, Avery Bang (Senior Principal, Mulago Foundation), institutionally independent of Virridy and of every implementer. Virridy competes for fund-supported work on the same terms as every other implementer; the verification standard is open and non-proprietary; health and water-quality evaluation sits with institutionally separate partners.

07Cost-Effectiveness and Scale

Against Renaissance Philanthropy's thresholds

<$100 per DALY averted · primary metric
Per-student program cost on the order of $1.50 per year, with documented health effects. Because third-party revenue carries delivery, the marginal donor cost per averted DALY falls toward zero over the program's life. A rigorous cost-per-DALY, built to GiveWell's own model, is a direct output of the independent, GiveWell-partnered evaluation now in design.
<$1/tonne
Proof the revenue engine works: the portfolio produces credits at ~$8.45 per tonne against a weighted-average contracted price of $21.26, so production is revenue-positive. The philanthropic input is the one-time catalytic layer, well under $1 per tonne at target scale.
~4:1
historical commercial-to-concessional leverage in blended finance; this $30M ask is already paired with $10M of Bridges debt (a ~$40M blend), and the $20M new-programs tranche extends the pattern across the implementer class.
9M
people served at full portfolio scale (2.79M today)
7.6M
credits (tonnes CO₂e) and ~$176M gross credit revenue modeled through 2033
1.2B
people boil drinking water. The open verification standard is what puts billion-tonne-order impact within reach, which is why the fund invests in the standard, not only its own programs.

Figures are illustrative and refined at structuring. Both thresholds are evidenced by one measurement layer: the continuous verification that prices the credit is the same data that populates the cost-per-DALY model. The full cost-per-DALY machinery, with a worked program example and the model pipeline, is published in the technical annex.

Read the full cost-effectiveness technical annex →

08Evidence Base

One protocol, six countries, randomized health evidence

29% / 25%
reductions in under-five diarrhoea and child acute respiratory infection in a cluster-randomized controlled trial of water filters and cookstoves in Rwanda (Kirby et al. 2019, prevalence ratio 0.71, 95% CI 0.59 to 0.87)
5.6×
benefit-cost ratio of that Rwandan program: $66.7M in benefits against an $11.9M investment over five years (Barstow et al. 2019), program-wide, dominated by fuel and time savings
Xylem · Veralto · AFRL
independent commercial demand: Xylem deploys the Lume on the Potomac; Veralto (Hach, In-Situ, OTT) holds a channel partnership; the U.S. Air Force Research Laboratory is evaluating it for Air Force and Army water security

The randomized signal is strongest for household filtration; the portfolio-wide monitoring is what generalizes independently verified performance across the other modalities and countries. What remains to be financed is shared validation and acceptance, not whether the approach works.

09Leadership and Team

Independent fund management, operating depth, separate evaluators

Avery Bang
Proposed Chief Fund Manager and Deal Flow Manager

Senior Principal at the Mulago Foundation, where she leads sourcing and the fellows portfolio, finding and funding high-performance organizations addressing global poverty and climate. Previously CEO of Bridges to Prosperity for more than a decade, scaling it to serve 1.4M+ people across twenty countries. MBA, Saïd Business School, Oxford; MS Civil Engineering, CU Boulder; BS Civil Engineering and Studio Art, Iowa. Her institutional independence from Virridy and from every implementer anchors the fund's governance separation.

Evan Thomas
Proposed Co-Fund Manager, Program Director, and Field Strategist

Professor and Director of the Mortenson Center in Global Engineering and Resilience at CU Boulder; Founder and CEO of Virridy. PhD Aerospace Engineering Sciences, MPH, MBA, PE; formerly NASA and DelAgua Health. 85+ peer-reviewed publications, seven patents. Developed the first UN CDM and Gold Standard programs earning carbon credits for household water treatment; now oversees safe-water carbon programs in six countries. IWA Water and Development Research Award (2025).

Implementation, carbon, and technical team

Virridy is organized as three coordinated entities mirroring the fund's commercial/philanthropic separation: Virridy Digital (builds and sells the Lume), Virridy Carbon (Gold Standard registered project developer), and Virridy Rwanda (field operations). $5.9M revenue in 2026, nearly 3× prior year; backed by non-dilutive funding from NSF, NASA, USAID, and the Gates, Moore, and Walton foundations.

Independent evaluation

Health and water-quality evaluation sits with partners institutionally separate from implementation: Matthew Freeman and Thomas Clasen (Emory), Rachel Peletz (Aquaya Institute), Corey Nagel (University of Arkansas, biostatistics). The parties measuring outcomes have no operational stake in the interventions they assess.

10Why Now, and What Could Go Wrong

The standard for this credit class is being written now

The carbon market's integrity reckoning is a tailwind: buyers and regulators are moving toward evidence-backed credits, and Gold Standard's Pilot 14 opens a window to define the safe-water standard on continuous, objective measurement before low-integrity credits define the class instead.

Methodology risk
Pilot 14 is already granted; validation is designed to registry evidentiary requirements; the team wrote the first UN CDM and Gold Standard water-treatment methodologies.
Carbon-price and market risk
$25M of long-term contracted offtake with compliance and Article 6 buyers reduces spot exposure; high-integrity credits are the segment most insulated from discounting.
Adoption risk
The standard is open, non-proprietary, and lowers every implementer's own verification cost; capacity and demand-aggregation functions actively support uptake.
Integrity risk
This is the problem the fund exists to solve: continuous objective measurement plus institutionally independent evaluation.
Concentration risk
The method is device- and modality-agnostic and vendor-neutral; independent adoption by Xylem, Veralto, and AFRL shows viability beyond the fund's own programs.
11The Ask

$30 million, as anchor donor

A commitment from Renaissance Philanthropy to capitalize the Water for Health Fund, in two tranches: $10M deployed immediately into the existing footprint, where monitoring, offtake, and implementers are already in place, and $20M bringing new programs, implementers, and delivery models to creditable, financeable status. The fund reports against one primary metric: the marginal donor cost per averted DALY, evaluated independently to GiveWell's own model.

We would welcome Renaissance Philanthropy's role not only as anchor donor but as fund-structuring and governance partner, convening the wider coalition of climate, water, and carbon-integrity funders around the thesis over the fund's term.