placestats

Basic water access vs. Fertility rate

Holds up after adjusting for income

Across 197 countries, Basic water access and Fertility rate rise and fall together at r = -0.82 (on a scale from −1 to +1, where 0 means no link). Comparing only countries with similar income (GDP per person) shrinks it to -0.49 (q = 0.013, allowing for the many pairs tested). Much of the first figure is that both measures rise with national income, but a moderate negative link remains. Caution: direction is not consistent across regions.

Comparing countries across the middle half of fertility rate, 1.45 to 3.12 births per woman, basic water access is worse by 15.2% of population at the top of that range than the bottom. Comparing only countries with similar national income, the gap is 10.2% of population.

Link before adjusting (r)-0.815p = 3.7e-48 · 197 countries
After adjusting for national income-0.487p = 4.7e-13 · likely range [-0.59, -0.37]
p, allowing for regions0.001standard error 0.081 · 7 regions
Check for luck (q)0.013across 12,497 pairs

How to read these.r runs from −1 (one goes up as the other goes down) to +1 (they rise together), and 0 means no link. Adjusting for national income means comparing countries with the same GDP per person, so differences in wealth can’t explain the link. Income is used in percentage terms, since an extra $1,000 means more to a poor country than to a rich one. p is how likely a link this strong would be if there were really none. Below 0.05 means it is unlikely to be chance. Very small values are written in short form: 1.1e-32 means a decimal point followed by 31 zeros and then 11, so very close to zero. The likely range is where the true figure probably lies, and a range that crosses zero means the link could easily be chance. Countries in the same region tend to resemble each other, so the third figure allows for that, which gives a fairer p. The standard error is the typical size of the error in r. Finally, testing this many pairs means some will look strong by luck alone. A q below 0.05 means this link is unlikely to be one of those.

Basic water access · % of populationlink with income +0.85 · proxy
Fertility rate · births per womanlink with income -0.81 · proxy

Both of these rise and fall closely with national income, so a strong link between them before adjusting was close to certain. Read the adjusted figure, not the first one.

“Link with income” is how closely each measure tracks GDP per person across countries, from −1 to +1.

Every country as a dot

Basic water access · % of population →Fertility rate · births per woman →35.7%100%0.5826.03Aruba: 96.7% of population, 1.61 births per womanAfghanistan: 80.8% of population, 4.76 births per womanAngola: 68% of population, 5.05 births per womanAlbania: 95.1% of population, 1.34 births per womanAndorra: 100% of population, 1.09 births per womanUnited Arab Emirates: 100% of population, 1.21 births per womanArgentina: 99% of population, 1.5 births per womanArmenia: 99.9% of population, 1.7 births per womanAntigua and Barbuda: 98.9% of population, 1.58 births per womanAustralia: 100% of population, 1.48 births per womanAustria: 100% of population, 1.31 births per womanAzerbaijan: 97.7% of population, 1.43 births per womanBurundi: 65.9% of population, 4.79 births per womanBelgium: 100% of population, 1.44 births per womanBenin: 69.6% of population, 4.48 births per womanBurkina Faso: 50% of population, 4.11 births per womanBangladesh: 98.8% of population, 2.14 births per womanBulgaria: 99.2% of population, 1.72 births per womanBahrain: 99.9% of population, 1.8 births per womanBahamas, The: 98.9% of population, 1.37 births per womanBosnia and Herzegovina: 96.1% of population, 1.49 births per womanBelarus: 99.9% of population, 1.22 births per womanBelize: 94.8% of population, 2.02 births per womanBermuda: 100% of population, 1.41 births per womanBolivia: 93.4% of population, 2.52 births per womanBrazil: 100% of population, 1.61 births per womanBarbados: 99.2% of population, 1.71 births per womanBrunei Darussalam: 100% of population, 1.73 births per womanBhutan: 99.5% of population, 1.45 births per womanBotswana: 91.8% of population, 2.7 births per womanCentral African Republic: 36.5% of population, 5.95 births per womanCanada: 98.3% of population, 1.25 births per womanSwitzerland: 100% of population, 1.29 births per womanChile: 99.1% of population, 1.14 births per womanChina: 96.1% of population, 1.01 births per womanCote d'Ivoire: 77.2% of population, 4.23 births per womanCameroon: 71.4% of population, 4.26 births per womanCongo, Dem. Rep.: 35.7% of population, 5.98 births per womanCongo, Rep.: 73.5% of population, 4.11 births per womanColombia: 97.1% of population, 1.63 births per womanComoros: 85.1% of population, 3.82 births per womanCabo Verde: 92.3% of population, 1.51 births per womanCosta Rica: 99.8% of population, 1.32 births per womanCuracao: 100% of population, 1.4 births per womanCayman Islands: 95.5% of population, 1.52 births per womanCyprus: 99.7% of population, 1.38 births per womanCzechia: 98.7% of population, 1.36 births per womanGermany: 100% of population, 1.36 births per womanDjibouti: 79.7% of population, 2.62 births per womanDominica: 97% of population, 1.48 births per womanDenmark: 100% of population, 1.47 births per womanDominican Republic: 97.5% of population, 2.22 births per womanAlgeria: 92.4% of population, 2.72 births per womanEcuador: 92.1% of population, 1.81 births per womanEgypt, Arab Rep.: 97.3% of population, 2.73 births per womanSpain: 99.9% of population, 1.1 births per womanEstonia: 100% of population, 1.18 births per womanEthiopia: 55.6% of population, 3.91 births per womanFinland: 100% of population, 1.25 births per womanFiji: 95.6% of population, 2.27 births per womanFrance: 100% of population, 1.61 births per womanFaroe Islands: 100% of population, 1.91 births per womanMicronesia, Fed. Sts.: 89.9% of population, 2.74 births per womanGabon: 88.6% of population, 3.59 births per womanUnited Kingdom: 100% of population, 1.55 births per womanGeorgia: 97.3% of population, 1.8 births per womanGhana: 89.9% of population, 3.34 births per womanGuinea: 74.2% of population, 4.13 births per womanGambia, The: 87.1% of population, 3.91 births per womanGuinea-Bissau: 61.8% of population, 3.76 births per womanEquatorial Guinea: 64.7% of population, 4.12 births per womanGreece: 100% of population, 1.24 births per womanGrenada: 95.6% of population, 1.47 births per womanGreenland: 100% of population, 1.71 births per womanGuatemala: 93.2% of population, 2.29 births per womanGuyana: 95.6% of population, 2.4 births per womanHong Kong SAR, China: 100% of population, 0.841 births per womanHonduras: 95.7% of population, 2.48 births per womanCroatia: 99.9% of population, 1.46 births per womanHaiti: 73.3% of population, 2.63 births per womanHungary: 100% of population, 1.41 births per womanIndonesia: 89% of population, 2.12 births per womanIndia: 95.7% of population, 1.96 births per womanIreland: 97.1% of population, 1.47 births per womanIran, Islamic Rep.: 97.9% of population, 1.68 births per womanIraq: 98.4% of population, 3.22 births per womanIceland: 100% of population, 1.56 births per womanIsrael: 100% of population, 2.87 births per womanItaly: 99.9% of population, 1.18 births per womanJamaica: 87.6% of population, 1.35 births per womanJordan: 99.3% of population, 2.6 births per womanJapan: 99.2% of population, 1.15 births per womanKazakhstan: 97.8% of population, 2.98 births per womanKenya: 65.6% of population, 3.17 births per womanKyrgyz Republic: 94.9% of population, 2.6 births per womanCambodia: 82.8% of population, 2.55 births per womanKiribati: 79.1% of population, 3.12 births per womanSt. Kitts and Nevis: 98.6% of population, 1.53 births per womanKorea, Rep.: 100% of population, 0.748 births per womanKuwait: 100% of population, 1.56 births per womanLao PDR: 95.9% of population, 2.4 births per womanLebanon: 92.6% of population, 2.23 births per womanLiberia: 78.8% of population, 3.86 births per womanLibya: 96.4% of population, 2.3 births per womanSt. Lucia: 98.1% of population, 1.39 births per womanSri Lanka: 90.2% of population, 1.95 births per womanLesotho: 78.1% of population, 2.66 births per womanLithuania: 99.9% of population, 1.11 births per womanLuxembourg: 100% of population, 1.25 births per womanLatvia: 98.8% of population, 1.24 births per womanMacao SAR, China: 100% of population, 0.582 births per womanMorocco: 92.2% of population, 2.21 births per womanMoldova: 92.7% of population, 1.73 births per womanMadagascar: 55.3% of population, 3.91 births per womanMaldives: 99.8% of population, 1.56 births per womanMexico: 99.5% of population, 1.89 births per womanMarshall Islands: 87.4% of population, 2.86 births per womanNorth Macedonia: 98.2% of population, 1.4 births per womanMali: 86.4% of population, 5.51 births per womanMalta: 100% of population, 1.01 births per womanMyanmar: 85.7% of population, 2.1 births per womanMontenegro: 99.3% of population, 1.8 births per womanMongolia: 86.1% of population, 2.5 births per womanMozambique: 66.6% of population, 4.69 births per womanMauritania: 77.3% of population, 4.63 births per womanMauritius: 99.9% of population, 1.44 births per womanMalawi: 73.1% of population, 3.59 births per womanMalaysia: 97.9% of population, 1.54 births per womanNamibia: 86.5% of population, 3.21 births per womanNiger: 53.4% of population, 5.93 births per womanNigeria: 82.2% of population, 4.38 births per womanNetherlands: 100% of population, 1.43 births per womanNorway: 100% of population, 1.45 births per womanNepal: 93.6% of population, 1.96 births per womanNaoero: 97.8% of population, 3.29 births per womanNew Zealand: 100% of population, 1.57 births per womanOman: 92.7% of population, 2.51 births per womanPakistan: 90.7% of population, 3.55 births per womanPanama: 95.3% of population, 2.11 births per womanPeru: 95.6% of population, 1.97 births per womanPhilippines: 95.9% of population, 1.89 births per womanPalau: 99.5% of population, 1.88 births per womanPapua New Guinea: 53.3% of population, 3.07 births per womanPoland: 90.1% of population, 1.14 births per womanPuerto Rico (US): 100% of population, 0.92 births per womanPortugal: 99.3% of population, 1.41 births per womanParaguay: 99.6% of population, 2.42 births per womanWest Bank and Gaza: 98.8% of population, 3.25 births per womanQatar: 100% of population, 1.72 births per womanRomania: 100% of population, 1.39 births per womanRussian Federation: 96.9% of population, 1.42 births per womanRwanda: 61.4% of population, 3.65 births per womanSaudi Arabia: 99% of population, 2.31 births per womanSudan: 64.9% of population, 4.26 births per womanSenegal: 88% of population, 3.77 births per womanSingapore: 100% of population, 0.97 births per womanSolomon Islands: 71.6% of population, 3.51 births per womanSierra Leone: 68.1% of population, 3.7 births per womanEl Salvador: 91.6% of population, 1.77 births per womanSan Marino: 100% of population, 1.16 births per womanSomalia, Fed. Rep.: 75.3% of population, 6.01 births per womanSerbia: 95.4% of population, 1.64 births per womanSao Tome and Principe: 78% of population, 3.6 births per womanSuriname: 98% of population, 2.23 births per womanSlovak Republic: 99.8% of population, 1.46 births per womanSlovenia: 99.6% of population, 1.52 births per womanSweden: 99.8% of population, 1.43 births per womanEswatini: 80.4% of population, 2.72 births per womanSint Maarten (Dutch part): 99.3% of population, 1.44 births per womanSeychelles: 97.7% of population, 1.85 births per womanSyrian Arab Republic: 94.1% of population, 2.7 births per womanTurks and Caicos Islands: 98.8% of population, 1.45 births per womanChad: 52.2% of population, 6.03 births per womanTogo: 64.8% of population, 4.12 births per womanThailand: 100% of population, 1.2 births per womanTajikistan: 89.2% of population, 3.04 births per womanTurkmenistan: 99.9% of population, 2.66 births per womanTimor-Leste: 87.3% of population, 2.63 births per womanTonga: 98.9% of population, 3.1 births per womanTrinidad and Tobago: 99.3% of population, 1.54 births per womanTunisia: 96.7% of population, 1.82 births per womanTurkiye: 96% of population, 1.48 births per womanTuvalu: 98.7% of population, 3.17 births per womanTanzania: 64.6% of population, 4.54 births per womanUganda: 63% of population, 4.17 births per womanUkraine: 93.5% of population, 0.988 births per womanUruguay: 99.6% of population, 1.4 births per womanUnited States: 100% of population, 1.63 births per womanUzbekistan: 97.3% of population, 3.49 births per womanSt. Vincent and the Grenadines: 97.7% of population, 1.76 births per womanVirgin Islands (U.S.): 99.5% of population, 1.97 births per womanViet Nam: 98.8% of population, 1.9 births per womanVanuatu: 87.1% of population, 3.57 births per womanSamoa: 99.4% of population, 3.8 births per womanSouth Africa: 90.2% of population, 2.21 births per womanZambia: 73.4% of population, 4.04 births per womanZimbabwe: 67.2% of population, 3.67 births per womanBFACAFCODHKGKORMACMDGMLIPNGSOMTCDWSM

best-fit line line after adjusting

Four ways to measure the link

MethodrpCountries
Standard (Pearson), not adjusted-0.8153.7e-48197
By rank (Spearman), not adjusted-0.7705.6e-40197
Standard (Pearson), adjusted for national income-0.4874.7e-13197
By rank (Spearman), adjusted for national income-0.2600.000197

The rank version uses only each country’s place in line, from lowest to highest, so a few extreme countries count for less. The adjusted and unadjusted versions use the same 197 countries: those that report both measures and GDP per person. So the gap between them comes from the adjustment, not from a change in which countries are counted. Drop in the size of r after adjusting: +0.328 (a minus sign means it grew).

How solid is it?

Leaving out one country at a time, r ranges from -0.514 (without MLI) to -0.463 (without COD). The bar above shows that range on a scale from −1 to +1, with the solid line at the full result. The single country that moves r most: MLI (-0.027).

Fragile: this link may not hold up.
  • direction is not consistent across regions
  • much weaker within regions than across them (largely a between-region difference)

Within each region

Countries are not separate, unrelated cases, and neighbors share a lot. A link that holds inside each region is far more believable than one that shows up only when comparing regions.

nr
East Asia & Pacific31+0.08
Europe & Central Asia52+0.09
Latin America & Caribbean37-0.19
Middle East, North Africa, Afghanistan & Pakistan22-0.19
Sub-Saharan Africa46-0.40

By income third

If the link shows up only in the richest third of countries, it is a feature of rich countries, not a general pattern.

nr
Poorest third66-0.43
Middle third65-0.34
Richest third66-0.25

By largest religious group

Countries grouped by a label they share, such as main religion, rather than by a number. Groups of fewer than twelve countries are not shown. These groups differ in income, region and history all at once. So a gap between them is a place to start asking questions, not an answer.

nr
Christians111-0.61
Muslims49-0.42

By last european coloniser

Countries grouped by a label they share, such as main religion, rather than by a number. Groups of fewer than twelve countries are not shown. These groups differ in income, region and history all at once. So a gap between them is a place to start asking questions, not an answer.

nr
France25-0.42
Never a European colony21-0.30
Spain19-0.81
United Kingdom63-0.22

Without outliers (countries far outside the middle half of countries on either measure, by more than one and a half times the width of that middle half): r = -0.363 after dropping 22 countries.

Two series, one country

Both measures over the years for one country you pick. The two charts are stacked so they share only the years along the bottom.

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Over time, within countries

Everything above compares countries with each other at one moment. This section compares each country only with itself over 25years. So a link here can’t come from anything about a country that stays the same, such as its history, geography, institutions or culture.

The link also shows up within countries over time (r = -0.435). It holds even when looking only at changes from one year to the next (r = -0.234). This is the strongest kind of evidence available here: it holds when each country is compared only with itself, and it is not just a product of shared trends.

Across countries (adjusted)-0.487for comparison
Within countries-0.635each country vs itself
…and vs the same year elsewhere-0.435q = 0.000 · 214 countries
Year-on-year changes-0.234q = 1.0e-5
Read with care.
  • Almost all of this indicator's variation is between countries, not within them, so the within-country estimate rests on a small part of the data.
  • The association is much weaker in year-on-year changes than in levels, which points to shared country-specific trends.

5,209 country-years (one country in one year), 214 countries, 2000–2024, about 24 years each on average. Share of the variation that happens within countries over time: 6% for Basic water access, 6% for Fertility rate. The margins of error allow for each country appearing many times, and for each year’s value being close to the year before.

Year-to-year changes are a cautious test, not a final answer. Looking only at changes from one year to the next removes each country’s own trends. But it also makes measurement mistakes louder, which pulls the results toward zero. A near-zero result here is weak evidence of no link, not proof.

With one measure years behind the other

0.50−0.5-100+10years Fertility rate trails Basic water access →lag -10: r = -0.337 (n = 5,209)lag -9: r = -0.355 (n = 5,209)lag -8: r = -0.370 (n = 5,209)lag -7: r = -0.385 (n = 5,209)lag -6: r = -0.398 (n = 5,209)lag -5: r = -0.408 (n = 5,209)lag -4: r = -0.415 (n = 5,209)lag -3: r = -0.422 (n = 5,209)lag -2: r = -0.427 (n = 5,209)lag -1: r = -0.430 (n = 5,209)lag +0: r = -0.435 (n = 5,209)lag +1: r = -0.434 (n = 5,007)lag +2: r = -0.432 (n = 4,804)lag +3: r = -0.430 (n = 4,601)lag +4: r = -0.427 (n = 4,397)lag +5: r = -0.423 (n = 4,188)lag +6: r = -0.419 (n = 3,983)lag +7: r = -0.413 (n = 3,777)lag +8: r = -0.405 (n = 3,567)lag +9: r = -0.394 (n = 3,354)lag +10: r = -0.380 (n = 3,137)

Same year (lag 0): -0.435. A peak away from zero does not show which comes first. These series change slowly — this year’s value is close to last year’s. That makes the curve smooth and nearly symmetric, whatever produced the data. Even a sharp peak at one lag (a gap of some years) would not prove that one measure changes the other.

The data


% of population
births per woman		Years
Thailand THA100%1.22024
Singapore SGP100%0.972024
Puerto Rico (US) PRI100%0.922024
New Zealand NZL100%1.572024
Norway NOR100%1.452024
Netherlands NLD100%1.432024
Malta MLT100%1.012024
Macao SAR, China MAC100%0.5822024
Luxembourg LUX100%1.252024
Kuwait KWT100%1.562024
Korea, Rep. KOR100%0.7482024
Iceland ISL100%1.562024
Hungary HUN100%1.412024
Hong Kong SAR, China HKG100%0.8412024
Greenland GRL100%1.712024

World Bank, World Development Indicators
World Bank, World Development Indicators

Sources

Basic water access

People using at least basic drinking water services (% of population)

World Bank · CC BY 4.0 · updated quarterly

Fertility rate

Fertility rate, total (births per woman)

World Bank · CC BY 4.0 · updated quarterly

How this was computed

Data used: most recent value in 2010-2025; values come from 2016–2024. To adjust for income, each measure is first predicted from GDP per person (in percentage terms, on a log scale) with a straight-line fit. Only what is left over is then compared. This is called a partial correlation. The line is drawn the standard way (ordinary least squares), which picks the line that comes closest to all the countries at once. The error margins allow for countries in the same region resembling each other, using 7 World Bank regions. The q-value corrects for testing all 12,497 pairs at once, using the Benjamini–Hochberg method. Underlying data last updated DYB 2024. How the country data works · explore Basic water access and Fertility rate

This page shows that two measures go together. It does not show that Basic water access changes Fertility rate, or the reverse. These figures also describe countries, not individual people. See the ecological fallacy.

More links with Basic water access or Fertility rate